Isshinsai Ogata is the Ancient Martial Arts Master and Saint Fist of Yami's One Shadow, Nine Fists. He is the former master of Ryūto Asamiya and the second man introduced who walks down the Path of Asura, after Sōgetsu Ma.
Ogata is a tall man with long purple hair down to his waist with a muscular build and a calm face. He is usually seen with a cloak on and bandages around his wrists. He wears a buckle belt around his waist and a small side pouch, which he uses to carry his items.
Like Alexander Gaidar and Diego Carlo, he possesses a far angrier side under his calm and composed self, but with slightly more control, only getting angry when someone or something is looking for a fight or provokes him. Ogata appears to be a sociopath, able to, at a moment's notice, change his demeanor completely.
When he first meets Kenichi, he comes off as a kind man seeking atonement, whereas when he fights the bear, he shows his vicious nature, continuing to attack the bear even after it was already dead. Although he is ruthless and sneaky, it should be noted that he is immensely upfront about his intentions. He lets his disciple know what his intentions are and even Lugh is perfectly fine with the fact that he is being used as an experiment for new martial arts techniques that can be dangerous. Although Ogata warns his disciples about dangerous techniques. He still wants his disciples use the techniques but he never forces them.
However, despite Ogata's lack of morality towards human life, he has shown to have some sense of moral code. He despises people who needlessly kill without any sense of honor, and he is also shown to despise people who take advantage of those who cannot fight back. This is shown when he saves a young Natsu Tanimoto from the company members that tried to kill him, and when he berates said company people for bullying Natsu even though he couldn't fight back. When Mayu Tanaka attempted to kill him to avenge her father, Ogata did try to persuade her to not fight stating he doesn't want to kill such a young person, but would go all out should she continue, to which he killed her. Once he discovered she was pregnant at the time, Ogata seemingly regretted killing her, and this is heavily implied to be the reason that he originally isolated himself to seek atonement in the mountains where he meets Kenichi. This was shown again when fighting Kenichi, stating he didn't want to kill him, but would, should he continue. He seems to choose to go all out when his opponents respond at full strength as a sign of respect.
Although he is a Satsujinken, Ogata has a martial arts code. He believes everyone is equal in the world of martial arts, but he will only kill a person if they are attacking him with killing intent. Likewise he himself encourages his own disciples to one day surpass and kill him, showing that he even views his own life as a stepping stone to advancing martial arts. Odin noted that when facing multiple opponents, Ogata will attack the first fighter who assumes a defensive stance. Ogata does however, have one reoccurring pattern: if he stops to praise his opponent, he will leave himself open for a short period of time.
Despite his cruelty in battle, Ogata has a genuine love and appreciation for martial arts. He believes that martial arts should be pure and that one should not bring their emotions or grudges into their fights. His respect for martial arts is so pure that he stated that he would gladly be criticized for killing someone and even let them call him a "Murderer." Even Kenichi stated that he could not completely hate someone whose love for martial arts was so sincere. This sentiment was also shared earlier by Takeda who says that he is much like his master James Shiba who also has sincere love for boxing.
Ryūto respects him much like the other YOMI members with their masters. However, Ogata seems to have a two sided relation with his disciple; he trains Ryūto with several extremely high level techniques, but also uses him as a test subject for his untested techniques like the Seidō Gōitsu without caring for his well being.
He seems to get along with the other Yami members despite being a new member, most likely for his high strength and skill as a martial artist. However, he seems to be rather cautious around Mikumo due to her being much stronger and even commented on how terrifying she is from her ki.
Ogata seems to harbour a strong animosity towards the Katsujinken, claiming it to be weak and those who follow it are soft in battle due to there refusal to kill their opponents and that their feelings hold them back and claim it makes them hard to deal with. It is this attitude that seems to have made him leave Ryōzanpaku, having such strong killing intent.
Ryūto noted that Ogata has one weakness in his skills: his pride. As noted by Ryūto, Ogata will not hesitate to praise disciples, whether they be his own or another master's. when Ogata is too busy praising Kenichi's managing to touch his face to notice Ryūto charging in to attack.
Despite be a follower of the Satsujinken, and a very vicious fighter, Ogata has been shown to have a very merciful side to him, and has been shown to actually display that mercy even to his disciples. This was shown when he picks up Lugh when leaving with Berserker and allows Ryuto to stay with Rimi and not return with him back to Yami. It was revealed that before Rimi died from the overuse of the Seidō Gōitsu, he stopped Rimi's Ki flow and deactivated it before it killed her. He even took a look at Ryūto, apparently disappointed but still did not try to stop or kill him for his decision to betray his master, showing that even though he is a Satsujinken, he is willing to allow his targets to live.
One of the most admirable side of Ogata is him respecting other people path they choose in life. After saving the young Natsu Tanimoto, he encouraged said boy to learn martial arts not for the sake of becoming a Satsujinken, but for the sake of becoming a leader and earning respect so that his life would never be in danger again. In the mountain when he first met Kenichi, he encouraged Kenichi to walk his own path in life and to follow his heart as oppose to trying to get Kenichi to become a satsujinken. In the epilogue, once he found out that Lugh and Berserker went up against yami armed division, instead of getting mad, he complimented them for their decision despite the fact that Ogata and Kushinada were the only OSNF masters who did not switch sides and were fighting alongside the Yami armed division. He is willing to praise his last two disciples about going against his orders for not killing the members of Shinpaku Alliance.
Ogata was originally going to be the very first disciple of Ryōzanpaku before Kenichi. However, the Elder saw he had evil intentions. Ever since this time Ogata harbors a great extent of dislike against Hayato Fūrinji. Though Akisame Kōetsuji and Kensei Ma intended to train him against the Elder's recommendation. After leaving he joined a competition and killed one of the his opponents. Sometime after he met up with Ryūto, who was witnessing his fight with two armed opponents. He quickly defeated them and showed Ryūto that martial arts killing still exists and took him in as his disciple. Training Ryūto for a few years and making Ragnarök and Eight Fists pick new Disciples to train.
At some point he used Kai Midō, who trained alongside Ogata during their days at Ryōzanpaku ,and who was affected with an unknown illness, in martial art experimentation. After having a fight to the death at Midō's dojo, he killed him and later his daughter Mayu Tanaka and her unborn son, leading his son-in-law, and only disciple Tsutomu Tanaka to walk down the path of revenge.
Despite all the deaths he has caused over the year, he only regrets was indirectly killing Tanaka's unborn son due to the fact that Ogata believes people should have the ability to pick their path in life and they should not die in vain. In fact this seemed to have been the reason why he withdrew from society and took residence in Yamigadani where he constantly build sculptures as a way of atoning.
While the newest member of the Yami, Isshinsai has clearly cemented himself as one of its greatest powers. Since a young age, Isshinsai showed great potential for the martial arts. His talents were great enough that Ryōzanpaku originally considered him to be its sole disciple. A truly fierce fighter, all known opponents to have faced him, have either ended up brutally killed or left seriously injured. One of his greatest (and more infamous feats) was his ability to defeat and kill Kai Midō and Mayu Tanaka, both master-level opponents in successive fights. He also recently defeated and killed Tsutomu Tanaka, another master of Tenchi Mushin Ryuu.
- Master Teacher: It has been noted that out of all of the One Shadow Nine Fists, Isshinsai is the most diligent one when it comes to training his disciples. Despite his lack of compassion, he has been noted by Hayato Fūrinji to be a remarkably skilled teacher, able to not only unlock large amounts of his students' potential skills in relatively short amounts of time, but also match his teaching methods to each disciples' individual skill sets. Examples include Odin, Berserker, Rimi and Lugh, who have all shown tremendous progress in their respective skills under his tutelage in spite of their wildly different combat styles. While a ruthless teacher, he does not shy from giving praise to his disciples for their growth as martial artists. However he is also prone to use his students as test subjects in order to teach them powerful yet self-destructive techniques such as the Seidō Gōitsu.
- Immense Strength: Befitting his large build, Isshinsai has demonstrated remarkable strength. During his brief performances in battle, he was able to balance and support his entire weight horizontally on a pole and throw an Asian bear, both feats with a single hand. He was able to repel one of Miu's flying kicks, tossing her aside with great force and knocking her out in the process with one punch and minimal effort. He was also able to knock out Kenichi, a disciple whose key feature is endurance by striking him with one finger to the heart. He even managed to stop a two finger, point-blank strike from a Seidō Gōitsu-empowered Ryūto with his bare teeth showing massive jaw strength. Another testament to his strength was his ability to completely crush Tanaka's skull with an overhead elbow strike.
- Immense Physical Prowess: Through years of creating his own personal style, Ogata has physically conditioned himself in the ways of various different types of ancient styles and training exercises in order to better increase his prowess as a martial artist. Ogata possess incredible reflexes, being capable of blocking point-blank strikes at the very last second. He has also shown incredible flexibility and dexterity, able to extend one leg straight up while standing on his other and balance a full-grown man on his extended leg. His physical durability is immense, enough to take one of Tanaka's last techniques undamaged while Tanaka's hands were damaged in the impact. Ogata has great stamina, able to defeat and kill Kai Midō and later defeat and kill Mayu Tanaka, despite receiving further injuries.
- Immense Dual Ki: When worked up, Isshinsai can be seen emitting a powerful and intimidating aura. It is so powerful, that Kenichi was shocked to see the seemingly kind Isshinsai capable of such power. Takeda noted that despite his calm and friendly appearance is that of a terrifying aura underneath, and yet, he states he's someone you can't come to hate. He believes it's due to his genuine love for martial arts. Though possessing and specializing in the use of Dou Ki, he can also attain and use it's counterpart, Sei Ki to an equally skilled degree, capable of using one of it's most advanced techniques, the Seikūken. He is also one of the rare fighters that can combine both types of ki.
- Master Manipulator: Isshinsai is a very crafty and charismatic man, able to skillfully deceive allies and foes alike to suit his needs. His most common tactic is to take the appearance of a kind-hearted and generous man to win over their trust or use profound speeches on individuals with conflicted emotions. He is also good at using other's feelings against him to his advantage, having used Tanaka's desire to avenge his master to kill him causing Tanaka to lose his calmness.
- Master Mixed Martial Artist: Isshinsai is a master of his own modified style of multiple Ancient Martial Arts, as such he is a very versatile fighter and a master of mixed martial arts. Isshinsai's fighting style comes from extensive research and training into various other styles that are considered ancient and practically extinct before modifying them into his own personally-made Ogata-Style. Through his years and journey to passionately improve his prowess as a martial artist, Isshinsai has accumulated a vast amount of knowledge if not skill in various styles. During his short time at Ryōzanpaku, Isshinsai learned much from the masters' various different combat forms, including at least one of the Elder's personal techniques. He also learned techniques of the Tenchi Mushin Ryū, though his degree of skill on this style is unknown. Isshinsai has also spent much time in not only developing his own original techniques, but has put much effort into teaching them to his various students with different combat styles to use them as test subjects to further refine the said techniques. His skill in martial arts is such that he can avoid an enemy's strikes, while purposely mimicking their blows and attack power all with great ease. Ryūto gave a bit on insight into his master's fighting style, noting that he would typically strike at the first person to assume a defensive stance and that the greatest opening to attack him is when he is praising his opponent.
He is fully seen when he goes into the mountains of Yamigadani, where he meets Kenichi. He shows Kenichi the path of Asura (which Hayato wanted Kenichi to witness) and it seems he grows an interest in Kenichi, wanting him to become his disciple, though Kenichi turns him down. After learning why Kenichi came to the mountains of Yamigata, he leaves to watch his battle against his disciple. He seemed impressed at Kenichi's motivation and his ability of being able to switch to a different person. After his disciple decided to get serious, he tried to stop their fight in order to have both as his disciples, but was dissuaded by the Ryōzanpaku masters. When Kenichi defeated Ryūto, Ogata jumped in through the window to save his disciple from falling to his death. Before leaving, he tells Hayato that Yami has begun to move and tried to set up a massive explosion.
He is later seen on a boat asking Tenmon Li to dispose of Ryōzanpaku and gave him info of Ryōzanpaku's disciple (Kenichi) to kill him. He soon after meets with Akira Hongō and his disciple Shō Kanō during a televised meeting of the One Shadow, Nine Fists. As Ogata converses with the other Fists, a female spy attempts to steal a valuable disk, but despite managing to escape, the disk is taken back by Shō.
Ogata visits Alexander Gaidar in his art gallery. He accidentally angers Alexander, which almost causes him to attack. He asks if Ogata was the one to allow his disciple, Boris Ivanov, to attack Ryōzanpaku. Ogata replies that he was only following the One Shadow's orders since he is YOMI's overseer, and tells Alexander that he should be grateful to him for allowing Boris and his men to attack Ryōzanpaku first. As Ogata overlooks the ocean and exclaims that the war between Ryōzanpaku and Yami has begun, Alexander notes to himself that one must be cautious around Ogata.
Shortly before the start of the D of D tournament, Ogata and Hongō are seen watching Shō practice in the gravity chambers. Ogata threatens to kill a scientist for asking too many questions. He then gave Shō his approval to partake in the tournament, much to Hongō's reluctance until he heard that Ryōzanpaku would be participating as well.
After the D of D's ending (as well as its destruction by the United States military), Ogata is the first to apologize to Hongō for the death of his disciple, saying that it was a great loss to the organization. He goes on to explain that the military have Shō's body and it would be a good while until Yami can retrieve it. It greatly angers Hongō when he hears Ogata mentioning that the former's disciple died while protecting someone from Ryōzanpaku.
Ogata appears during a test run of Yomi member Rachel Stanley, along with the other masters who had lost their disciples. He recommends the girl to Jenazad, but when asked by Hongō on not taking care of his own disciple's issues, he claimed that he still wanted to stick with Odin, as he was still a worthy experimental subject. Also, he claimed to have taken up experimenting with disciple training with three other individuals, of which one whose silhouette greatly resembles Berserker.
Much later, he ordered Rimi to retrieve the data of Yami that Ryōzanpaku had acquired. He persuaded her by stating she could do it for Ryūto.
With Jenazad dead, Ogata and the other remaining members of Yami gathered to discuss the matter, but Ogata said nothing in the meeting. Afterwards, he would talk with Mikumo claiming that someone had a hand in Jenazad's influence with the Fūrinji household and thought that someone had a grudge against the invincible Superman. He states he just want to have an opinion of an elder and Mikumo just says maybe the aim of the person was to put a stop to Jenazad before he became a chaotic factor of the plan for the Eternal Sunset. She walks away with Ogata stating what a lively woman she is and laughs while walking away. The next day, Rimi would ask him to train her to become stronger and notices the look in her eyes is stronger than before and says their heading to the mountains. He puts her through brutal training and is impressed how she managed to climb up the mountain with her weights despite it being the first day. At night when Rimi asks if it's an impure thought to become stronger for someone you love, Ogata just says that humans all have motives based on their free will and she should not be ashamed of that being her motivation and she says she's relieved. The next day, he takes her to a waterfall and throws rocks at her and comments on her sharp reflexes. That night, he talks to her about how he took Ryūto to the mountains and about the Dou ki and when Rimi wants to train to obtain it while Ogata says they should take it slow but she says she's fine with the risks and Ogata agrees but says there is a high price she will have to have to pay.
He returns from training with Rimi in the mountains greeting his disciples thanking them for looking after the place. He goes on to say that the masters finding the old hideout was the plan and probably should have let them know and apologizes for that and notes all they did was destroy a bunch of pointless machines, but things like this are important as well. He then introduces them to the new Rimi having released her Dou ki and she's a completely different person. As Ryuto notices she's asleep, Ogata states when they finished training she was happy she was going to see Ryūto, but could barely sleep. After Rimi leaves to take a shower, Ogata asks Lugh about his fight and Lugh tells him about the disciples and he comments them being unusual. Ogata says that if they don't want to come to him, then it's time for his disciples to feed on them. He is then interrupted by Mikumo as she states his monopolization is not good and has Hermit, Rachel and Chikage assist on this matter, causing Ogata to say it is a ruckus now.
At night, as Takeda and Lugh continue to fight outside the mirror house, Ogata arrives and interrupts them stating they look like they're having fun. Noting the fun they are having, Ogata states he has no interest to interfere and tells them to continue with their death match. He tells Takeda that he's been trained well and that his moves are similar to Kushinada and notes it's impressive he can do something similar like her despite his age. He also mentions Lugh being a little troubled in his fight, but becomes excited after seeing Lugh having made a counter strategy against Takeda stating that is what makes martial arts fascinating. After Takeda lands a blow on Lugh, he points out how Lugh broke Takeda's left arm noticing how he looked as if he was aiming for the right arm, but was really going for the left. He then reacts shocked seeing Takeda release his Sei ki using his own strength. Seeing Lugh in a bind, he briefly gives him the advice to defeat him quickly despite him stating he can't give advice during a fight, but it's cause he cares for his disciple.
He acknowledges Takeda's skill in ki, but warns him that Lugh isn't so weak that he can defeat him with just that. When both charge at each other for their final moves, Ogata noted that the resulting development from their fight was going rather slowly. He continues to watch and notices Lugh purposely letting Takeda punch him in the ribs to grab his arm and prepares to kill Takeda by striking the medulla on the back of his neck. However, as Lugh is defeated by Takeda using a clinching move and a dual strike to the liver falling unconscious, Ogata scoffs noting he was his best hope in ki. When Takeda asks if he's thinking it's the end of him, Ogata says he's not disposing of him, but rather, since Lugh suffered a major defeat in the highlight of his fighting life, then his life as a martial artist comes to an end. But when Takeda retorts stating that when Kenichi beat him, he became stronger and is sure Lugh will to, surprising Ogata. He leaves seemingly satisfied by Takeda's words calling him a real Katsujinken before Takeda has a chance to stop him.
He then arives after Miu having defeated Rimi and notes how she held back and scoffs at the Katsujinken. He then says hello to Kenichi and as Kenichi approaches him, Kenichi, rather than angry, thanks Ogata for the time he saved in in the woods. Ogata says he's pleased seeing how well Kenichi has grown, and agrees with there different paths of Satsujinken and Katsujinken. As Rimi attempts to continue fighting, she begs Ogata to teach her "that technique" so she can continue fighting, which has Ogata smiling from her response. Ogata then gives her the last instructions and gives her permission to use it. As he watches Rimi completely overpowering Miu, Odin begs his master to stop her before she suffers the backlash from the technique. However, Ogata states he doesn't feel like stopping her, and points out to Ryūto that she wishes to get stronger for his sake and even he should know it by now. As Ryūto desperately tries to stop her, Ogata says it's no use as even he can't reach her now and her heart is now nothing more than a moving mass of martial arts.
After Rimi apparently dies from using Seidō Gōitsu, Ogata approaches her "dead" body and notes it's a pity as she was so talented. He states she didn't "die" in vain and it's another cornerstone for martial arts, realizing that one must keep their emotions under tight control as part of using the technique, and notes to train his next disciples in this. Miu then attacks in rage over Ogata's lack of care towards Rimi's "death", resulting in Ogata retaliating with a disabling blow, scoffing at her Katsujinken ways. Kenichi catches her and runs to Ogata and angrily punches him, surprising Ogata. As Kenichi prepares to face the Yami master, Kenichi says he'll beat him up and won't even touch him. Ogata, accepts Kenichi's challenge and faces him. Though the disciple fights to the best of his ability, Ogata severely outmatches him, avoiding Kenichi's attacks, while countering with the exact same strikes and power as his opponent, all with the greatest of ease. However he praises Kenichi's skills, endurance and tenacity, but as the, disciple continues to rise from the attacks again and again, Ogata decides to go for a killing blow, only to be stopped at the last second by Odin, who managed to miraculously stand on his feet.
Marveling at Ryūto having learned how to stand and fixing his ki control, he eagerly takes on both disciples, completely overwhelming the both of the with the intent to kill. Using Seidō Gōitsu, Ryūto uses the 30 seconds he's learned to control and kicks Kenichi to him to increase his speed. After creating a small opening, he kicks Kenichi to increase his speed enough to break through Ogata's defense. Although the master only takes a small graze, his marvels while laughing at being touched by a disciple class fighter that gives Ryūto a second opening which he quickly exploits by smashing Ogata from behind.
However, Ogata blocks Ryūto's attack with his mouth. As he throws Kenichi and avoids more of Ryūto's attacks, Ogata praises Ryūto for coming his life. As Kenichi is throw, Berserker and Ogata realize Seidō Gōitsu has reached its time limit and Ryūto intends to throw his life away as he goes in to attack Ogata. Before he can be hit by a killing blow, Tanaka Tsumoto blocks the attack while deactivating Ryūto's Seidō Gōitsu just as the time limit is reached. wondering who Tanaka is, Tanaka introduces himself and reveals he managed to land a blow on Ogata, greatly pleasing the Master. The two fighters then face off with the intent to settle things.
As they fight, Ogata is actually brought to his knees, much to everyone's shock, but Tanaka says he will kill him. Ogata marvels at Tanaka's skills noting he's now achieved the level of Master class. Tanaka notes he's going easy on him, to which Ogata states is cause he doesn't sense his killing intent. He continues to goad him into killing him as a Satsujinken. As Tanaka begins to give in to his urge to kill Ogata to avenge his master, the two fighters clash, resulting in a massive shockwave.
Both Tanaka and Ogata exchange a series of blows and at one point Tanaka manages to knock Ogata away. Ogata however continues to taunt him saying that he doesn't have enough killing intent to win. As Ogata stands, Tanaka pulls out his cellphone and tells his wife that their family trip to the park will be slightly delayed while he takes care of some 'personal business'. Just then Ogata kicks the phone out of Tanaka's hand which causes Tanaka to fly into a more violent rage. As the fight continues, Ogata starts to gain ground over Tanaka, and chastsizes him for his lack of killing intent, despite Ogata being the killer of his master, wife and unborn son. The two continue their pitched battle, and decide to finish it with same technique against each other. As their techniques clashed, Tanaka was eventually overpowered by Ogata's technique. Ogata explains his philosophy for martial arts and explains how great his love for martial arts really is. He explains how his respect for martial arts is so great that he would gladly be called a murderer, and then prepares to finish his fight with Tanaka. As their fight continues he listens to Tanaka's resolve for fighting and in turn tells him that he would record whatever techniques he was still hiding. Tanaka shows that he is able to not only keep up with Ogata, but also counter his attacks, something that Ogata himself noted. As Ogata congratulates Tanaka for being able to counter his moves, he counters Tanaka's move instead, which follows with Tanaka blinding Ogata and attempting to execute the finishing blow. In the process of this attack, Ogata destroys Tanaka's hands by crossing his arms on his neck ans Tanaka by all his strength sees them broken at the same time when they cross to touch his neck and he punches Ogata's chin to lift up his head to get to his throat like he couldn't get it by the neck and as he tries to finish Kensei by tearing his throat out with his teeth, Ogata finishes him off by crushing his skull with his elbow, which also destroys his spine as a result, effectively killing him.
After the fight Ogata states that he has carved all of Tanaka's techniques into himself, and decides to leave with Berserker, as he looks back to see Odin holding Atlantae in his arms, he only turns away with a disappointed look on his face, and disappears in the flames with Berserker, leaving the burnt down amusement park with him while carrying Lugh in his arm. He arrives back at Yami and sees the Weapons team pass him noting the phase for the final plan is getting to that stage.
Ogata is later seen along side all of the remaining Yami members standing greeting Seitarō Raigō and the rest of the Hachiō Danzaiba members. He later rides in a helicopter with the others and, upon arriving at their location, are surrounded by the Ryōzanpaku masters (minus Shigure and the Elder). When the masters fight together against the Yami masters, Ogata is around the others masters prepared to fight Ryōzanpaku. Once Ishida arrives to escort the masters inside, Sakaki is outraged which Ogata just comments on how Yami's influence has reached the higher levels of the government. Once Honmaki arrives to inform them of the Hachiō Danzaiba members being at the dock, the Ryōzanpaku masters realizes it was a diversion. He later leaves with the others after Saiga gives them the message of the beginning of the Eternal Setting Sun.
He was later seen in another country with Raigō preparing the Eternal Sunset. After returning home, Ogata is seen speaking up to break up the internal fighting, followed shortly by Edeltraft who yet again spoke a cryptic statement ("The drops of the silvery brook fall in mass over gladioluses."). Edeltraft makes another cryptic statement, which Ogata finally thinks he understands, before walking away. Mikumo Kushinada, along with the other members of the One Shadow Nine Fists, comments that cultural exchanges are difficult and Ogata responds that the masters also need to show some teamwork against their enemy.
Later Ogata, along side Mikumo, Sōgetsu, Mildred, Edeltraft, Marmaduke, Știrbey, Hongō, Agaard, Cyril, Rin, and Raki all faced off later against the masters and allies of Ryōzanpaku. When the Ryōzanpaku masters attack together against Mildred, it's revealed Kensei only ripped her garmets off below, which left Ogata surprised and questioned Sōgetsu if Kensei is his younger brother. After seeing Kensei injured Rin, Agaard, Știrbey and Mildred's bow, Ogata curses them and engages battle with the rest of Yami against Ryōzanpaku. After Edeltraft splits up the masters, Ogata was seen engaging James Shiba.
This did not last too long as he reveals to Akisame that Shiba left a while ago, much to Akisame's furry.
As the fight continues, he along with Sōgetsu Ma is merely observing the fights as oppose to ganging up on the Ryōzanpaku masters and once Kagerō Kii sacrifices his life in order to help Katsujinken fighters and help regain the pride of Satsujinken. Ogata notices that with the exception of himself and Kushinada, all OSNF members have switched sides and allied with the Ryōzanpaku masters in order to defeat the Hachiō Execution Blades.
Although its important to note that, despite the fact that Ogata has not allied himself with the Ryōzanpaku masters, he has also not jumped in and attacked any of them from behind or taken any cheap shots much like how Mihai and other Hachiō masters have been fighting and ganging up on Ryōzanpaku masters so far and that once James Shiba left, Ogata merely became a spectator of the master brawl.
As the master brawl intensified, Ogata finally took part in the fight by activating Seidō Gōitsu and in doing so, he was able to defeat Rahman who asked Ogata where he learned such an "Evil Technique" Ogata informed him that, to truly progress in martial arts you must be able to dirty yourself in the soils of martial arts, as Ogata was prepared to deliver the death blow to Rahman, Agaard threw a kick at Ogata which Ogata was able to easily catch Agaard's legs and slam him to the boulder and choke him out much to Apachai's shock and horror.
As the fight progressed, only people left standing are Ogata, Kushinada, Seitarō on Yami's side while every single Ryōzanpaku-ally and other Hachiō members have been defeated and now Ogata, Kushinada and Seitarō will be engaging with Sakaki, Apachai, Akisame and Kensei as a large explosion occurs at the masters' battlefield as the colliding auras cause a yin-yang symbol to form in the sky.
As the battle drags on, Mikumo notices the missile launch and gleefully states its their victory. However, this is short lived as the Elder arrives and destroys the missile at the last second. Realizing they lost, Ogata leaves and angrily tells the soldiers in the way to move with a frighting glare.
After the Eternal Sunset, he was last seen praising Berserker and Lugh for their defiant efforts in battle at his castle which implies that he is either still a part of Yami or that he still has Yami funds at his disposal.
- Vs two armed opponents (killed them both)
- Vs Kai Midō (won, killed him)
- Vs Mayu Tanaka (won, reluctantly killed her and her unborn child)
- Vs a wild bear (won, killed it)
- Vs Miu Fūrinji (won, though technically not a fight as she attacked him and he merely knocked her out)
- Vs Kenichi Shirahama and Ryūto Asamiya (undecided, interrupted by Tsutomu Tanaka)
- Vs Tsutomu Tanaka (won, killed him)
- Vs James Shiba (undecided, Shiba abandoned the fight)
- Vs Cyril Rahman (Won)
- Vs Agaard Jum Sai (Undecided, was winning)
- With Mikumo Kushinada & Hachiō Danzaiba (minus Ōganosuke Yogi & Mihai Știrbey) Vs. Ryōzanpaku (minus Hayato & Shigure), Sōgetsu Ma & Agaard Jum Sai (Lost)
- Ogata has killed everyone that practiced Tenchi Mushin Ryuu.
- The method he came down the bridge to save Tanimoto was similar to Mallakhamba which is an exercise method as well as a sport in India that aims to build the body up which is considered an ancient exercise method that Ogata incorporates in to his and his disciples training.
- Out of everyone in the series who called Kenichi talent-less, Ogata sees Kenichi as someone who possess talent and even called him a large block of potential of martial art as mentioned by Shō Kanō.
- "Isshinsai" is an alias (斎号, saigō). His real given name is unknown.
- He uses the medicine he carries in his side pouch to help injured animals he finds.
- Miu has mentioned that she has no memory of Ogata being at Ryōzanpaku, this might be due to the circumstances that the Elder and Miu had a tendency to go on world travel, while Akisame and Kensei Ma took care of the house. During this time Ogata may have started his training with Akisame and Kensei Ma.
- Both Ogata Isshinsai and Kenichi Shirahama seem to be a tribute to real life shoot boxer named Kenichi Ogata who happens to fight in kickboxing and shootboxing (kickboxing with throws) as well as being a 2nd dan in judo. The comparison has never been confirmed but it should be noted that Isshinsai and Shirahama are both mixed martial artists much like Kenichi Ogata who has fought in various combat sports.
- He has carved several hundreds of buddha statues. Which means that he has killed just as many people.