Rimi has shoulder-length blond hair, blue eyes and a well-endowed figure for her age.
She dresses in typical Gothic Lolita clothes; a dark dress that reveals her chest with straps across the middle, a type of headband up top and wears sleeves around her arms midway. On her legs are stockings and she normally wears high-heels made from gold that double as weights.
Rimi constantly refers to herself in the third person and is said by Kensei to be "the most honest" of his disciples. She, as seen in when she talked to Miu and Nijima, is a little too honest, as she is telling secrets to the enemy without herself noticing. She is also deeply in love with Ryūto, becoming more motivated when he compliments her. This is also displayed when she called Miu her (love) rival, since Ryūto didn't tell her about his past relationship with Miu. She also shows the typical teenage mindset as she has a blog or internet dairy which she unintentionally writes about her day to day life along with Ryūto Asamiya. Her love for him is so great that she wishes to be trained by Ogata to become stronger for his sake. Her love for Ryūto seems to border to obsession, having used the dangerous Seidou Gōitsu move, which resulted in Ryūto losing usage of his legs (and Rimi losing conscious from it later) all just to prove how strong she is and gain his attention. While Ryūto may seem unaware of her feelings, he does truly care for her, but refuses to admit any form of affections to her and tends to respond with his usual coldness.
She has shown to be aggressive, going as far as to brutally assault Thor with several kicks to his face and body to get the disk she was ordered to get. She's also not above insults, such as calling Thor constantly "fat" or "fat ass" to make him angry.
Rimi is somewhat of a flirt around men, as she is fond of dressing in odd outfits (typically designed for school wear) when she was training with Ogata and tried to please him while he was unamused. She also dressed in a teddy bear outfit when prepared to fight Miu and Takeda as Lugh noted she wanted to try it out on. Later on after her third battle against Miu she wore a nurse costume because she thought it would please a doctor.
Her training with Ogata has changed Rimi somewhat, as she's much more confident and aggressive in battle, as her third confrontation with Miu has her boasting and attacking wildly believing herself to be stronger than her now. She's also become much more arrogant, believing herself to be on a whole other level compared to Miu and seemingly sadistic, having gloated that the Satsujinken is required to become stronger with great risks.
Immense Speed: Like the rest of Ogata's disciples (minus Berserker), Rimi has learned the "Ogata style" of Ancient Martial Arts, which makes her both a practitioner of Ancient Martial Arts, as well as a Mixed Martial Artist. Rimi's primary ability as a martial artist is her immense speed, which allows her to outpace, outrun, and overwhelm her opponents in various ways, including hit and run, and barrage tactics. She could move at speeds so fast that she can do a full body check on multiple foes in an instant. Even Miu (who has reflexes against anyone who attacks her from behind) didn't even notice her. In her fight with Miu, it is revealed that she could accelerate her speed and power to the point where it surpasses Miu's by taking the CD and her Bra at the same time, even though she got tired after doing that. It was revealed that as part of Ogata's training, she uses solid gold shoes as weights, and when she takes them off, she uses her speed to its maximum. After her training in the mountains, her speed had increased even further that even Miu now can't keep up anymore and is able to overwhelm her constantly resulting in Miu having to keep her guard up just to keep up with her.
Enhanced Strength: Despite her slender frame, Rimi possessed deceptively high levels of physical strength. During her first fight against Miu, she was able to take down an opponent as large and resilient as Thor with some effort and a few kicks. After her training with Ogata, Rimi's raw physical strength seems to have increased tremendously. When fighting against Miu, she was able to physically overpower her, due to the effects of the Seidou Gōitsu, despite Miu's considerable strength and she noted that her attacks were much heavier and difficult to withstand than before.
Enhanced Endurance: Rimi had shown to have a strong amount of stamina and endurance, having taken several blows from Miu, while in her berserker form, and managed to continue fighting while ignoring most of them. Even when Miu gained control of her Dou Ki and dealt even more serious blows, Rimi was able to stay conscious and attempted to continue fighting, despite her lack of strength to stand. Her endurance is ultimately put to the test, when she performs Seidou Gōitsu in an extremely weakened state, and manages to maintain it's use for a fairly long period of time, before ultimately collapsing from the injuries.
Strong Dual Ki: According to Miu, she had no killing intent or any other heavy type of Ki that other martial artists possess. However, Kensei states that he has unlocked her Dou Ki and that she possesses almost as much of it as Miu does. Miu states because of her how much stronger her Ki is now that she lets it flow wildly that resulted in her dropping her guard for Miu to counter. Once releasing her Dou Ki, Rimi was much more powerful and leaves Miu unable to keep up and left with brutal injuries from her assault. She also has great control of her Ki, which allowed her to overcome Miu's berserk state and turn the tides in her favor. However during her training in the mountains, Kensei also taught her how to produce Sei Ki, noting that she had the same potential in it's use as Kenichi and Odin, making her the third disciple who can use and combine both ki types.
Innate Talent: According to Kensei, Rimi had a talent that only one in a thousand have. Even Miu considered her as a genius, though she noted that her skills were not perfected. This allowed her to grow by leaps and bounds under Kensei's tutelage, to the point where she could outmatch and overwhelm Miu, a more experienced fighter and prodigy in her own right on their third fight. Kensei also noted that like Odin and Kenichi, she was one of the few martial artists who possessed the ability to naturally learn how to use either Dou or Sei Ki, and again referred to her talent as unique when she used Seidou Gōitsu.
Keen Instincts: She had reliable instincts, since her instincts told her about the quality of the Shinpaku Alliance, that she wouldn't win a fair and square fight against Miu, and that she knows that her instincts are always right. Even Ogata himself praised and told Rimi to follow her instincts.
At one point, Rimi was fighting the leader of a gang called Titan and defeated the leader named Chronos while stating she's the new leader of Titan. However, the other members decided wasn't going to let her become the leader and turned on her and attacked her while she was tired from her fight. She couldn't defend herself, but Ryūto appeared and defeated them all for her stating she could have defeated them, but would have sustained permanent injuries. He says he likes strong people and invites Rimi to join his cause. She does so (while the latter was still in Ragnarök). She followed him so that one day that should they reunite she would be loved by him. This would later prompt her to join YOMI.
Later, as the Shinpaku Alliance walks out of Inspector Honmaki's room, Rimi observes them and is told to steal the disc from them. She attempts to steal the disc, only for Miu to interfere and the two fight each other. Rimi would be annoyed at Miu due to Rimi having remembered Ryūto's past history together, causing her to be jealous of her. As they fight, Thor would accidentally interrupt to help fight and get the disc back from her. Rimi then decided to take off her weight shoes and fight seriously. While forcing Miu to fight more seriously and even injuring her further, Thor would accidentally destroy the disc, prompting Rimi to state that she was meant to steal the disc and destroy its contents, and with the disc gone, she has succeed in her mission. She left, but promised Miu they would fight again someday.
After Junazard's death, Rimi would act shocked hearing of his death at the hands of another Yami member and recall her first encounter with
Junazard and how his mere presence terrified her. Later, she would eavesdrop on Ryūto's call with Kenichi and choose not to tell Ogata stating she's on Ryūto's side. When Ryūto leaves, she says she'll help push him, but Ryūto says he's fine and boosts himself upward with ease, prompting Rimi to be amazed saying she'd do anything for him while blushing. She followed Ryūto to the aquarium were he was going to meet Kenichi and bumped into Miu, she and Miu fought and she was shocked that Miu was even faster then she was and how she dealt heavy injuries despite her holding back. After they were busted by Kenichi and Ryūto, they were forced to stop fighting. She then got jealous when she saw Miu pushing Ryūto's wheelchair and she and Ryūto left the aquarium to talk another day and Ryūto asked her if she would push him witch she was excited about and happily pushed him but a little too fast as he said.
She is now in the mountains training under Ogata to get stronger to beat Miu. She trains very hard with logs tied on rope to her wrists and ankles and is forced to climb the mountains. She wears a school gym outfit thinking it was the best to train in (and to please Ogata) prompting him to force her into more training. At night, she asks him to aim to move up in the marital arts world for someone you love is a impure motive. 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 not and says she's relieved. The next day, she trains at a waterfall and wears a school swimsuit and dodges some of Ogata's rocks but her swimsuit comes undone embarrassing her. That night, she's relieved he didn't see her naked and says Ryūto will be the first to see her naked and then asks about the Dou ki and asks for her to gain Dou ki, but Ogata says they should take it slow but Rimi states she's fine with the risks and can handle it. Ogata agrees but states that their is a high price to learn it.
Having completed her training with Ogata, Rimi returns a completely different person. Having released her Dou ki she's now someone completely different and walks in emotionless, much to Ryūto's shock. He calls her name and she doesn't answer, but it's shown she's actually asleep causing Ryūto to wake her with a hand clap. She tries to get herself together noting she trained so hard in the mountains and then notices Ryūto and runs over to hug him saying she powered up a lot. She tells him that Ogata noticed she has a lot of Dou ki like Miu. Rimi then notices she hasn't bathed in a while and goes to take a shower, becoming upset she's appeared in front of Ryūto so dirty. She comes back out as Mikumo talks about them killing Kenichi and his friends stating she doesn't want to be left out while she was showering. She later arrives at the amusement park with the other YOMI members and comments she'll rip Miu to pieces. She then groups with Lugh (while in a teddy bear costume) as they fight Miu and Takeda and all of them wish for her to take her outfit off as it's annoying and she takes it off and lunges at Miu as they prepare their third match.
As they fight, Rimi constantly says her name and attacks much more viciously as Miu notes she's much stronger than before and Rimi says to herself she can win this. She continues to overwhelm Miu and asks her if she's ever used martial arts for the sake of love or for their loved ones since she's doing this for Ryūto, surprising Miu that he and even more so that Rimi reveals the other YOMI members are also here. She continues to overwhelm Miu and mock her stating she's much stronger than before, but becomes shocked that Miu pushed her back from taking her limiters off. As Rimi discovers that Miu has been holding back to not hurt her so much, Rimi declares she'll break her pride in front of Ryūto and they continue to clash as Miu now is getting the upper hand, prompting Rimi to realize she needs to take this seriously and takes her gold shoes off again. She lunges at Miu only for Miu to dodge and jump after the gold shoes, much to Rimi's frustration.
She chases after Miu and grabs her shoes as Miu finally grabs them Rimi takes them away and tosses them atop a castle. She tells them to take them after she defeats her stating she fights for love. As Miu tries to tell her the Satsujinken harms her loved ones (such as Ryuto), Rimi smiles devilishly that to gain power one must be willing to take great risks. She then unleashes her training from the mountains and kicks Miu with blinding speed and Miu is unable to keep up with her as Rimi continues to strike her from behind constantly as Miu
attempts to defend from her assault. While on the roller coaster ride, Miu gets on it as Rimi does also and continues to overwhelm her with Rimi marvelling over her new found speed as she prepares to end things with her Shin Genya no Tsubame technique only for Miu to counter being faster than Rimi sending Rimi back onto the ride. As Rimi demands to know how Miu got faster that she lowered her power to do so and is shocked that Miu followed her from her ki that its so strong it scatters and makes her distracted resulting in Miu delivering a kick to her head and into the water. She gets up and when Miu reveals she just learnt to use that move just now, Rimi responds with confidence that now it is her loss.
Confused, Miu admits her having trained in martial arts all her life yet has never fought someone who was her
age and have a hard time against. When Rimi asks if Miu would ever sell her soul for power she recalls her first time meeting Ryuto and how to gain power one must be willing to risk anything. Rimi then decides to go all out and releases her Dou ki while stating it's her downfall for her delay and that once she dies, she will become stronger than Miu. Rimi then unleashes her Dou ki and overwhelms Miu to the point she can't dodge Rimi's moves any more and gets hit with a brutal punch into the water. Rimi then approaches the fallen Miu and says it's her victory and delivers a powerful punch into Miu's back and she crashes into the water.
As she prepares to finish Miu with Ogataryuu Datotsusenpa, Miu suddenly activates her Dou ki berserker mode after her near death experience and blocks Rimi's blow and sends her backwards. She then punches Rimi back and the two, having unleashed there Dou ki causes them to fight in a wild frenzy all after going through the other YOMI fights with Shinpaku. They make there way to Ryūto's and Freya's location still fighting wildly as Miu seems to gain the upper hand as she loses control. Seeing Miu fight wildly, she realizes what Ogata meant about the Dou ki going berserk should you lose control. However, Rimi tells Miu the world of martial arts isn't so cut and dry that victory is determined by ones release of ki and deals a two-fisted punch in Miu's stomach, sending her back. However, Miu ignores her damage prompting Rimi to berate her for ignoring it more over Miu trying to damage her instead. Miu then charges with fury and gets behind Rimi as Rimi tries to swing her arm around as Miu jumps up unleashing a fury of fists only for Rimi to dodge them at the last second. Miu then runs to the other side of the peer and Rimi retreats and Miu rushes at her full speed striking her as they strike back and forth as Rimi notes Miu's ki surpasses her and if she makes one mistake she'll be done for. Rimi still refuses to lose and when Miu strike with her fist, Rimi pushes it upward and tells the berserk Miu that the proper usage of ki always surpasses those that use it wildly and thanks to Ogata's training will help her win her fight and delivers' point blank attacks on Miu's face. However, Miu continues to ignore the damage and they fight onward making there way to Kenichi fighting Berserker.
Sending Miu backwards into a building, Rimi tells the berserk Miu that even with her enormous power she'll still perish as long as she doesn't know how to use it. She then loses her concentration seeing Ryūto and covers herself from her tattered clothes. She believes he finished his opponent and came to witness her "heroic deeds" and tells him to watch as she kills Miu. She then lunges at her again with strikes all around as Miu continues to be dominated and hurled into the roof next to them, which has Rimi shout this will be the end of the Fūrinji bloodline and shouts for her to die. After Kenichi tries to awaken Miu, Rimi grabs Miu and throws her through the Merry-go-round ride. Standing above a seemingly unconscious Miu, Rimi tells Kenichi words won't reach her and attempts to kill her with her punch, but Miu blocks at the last second, shocking Rimi as Miu strikes Rimi's sides sending her backwards. Rimi then stares angry at Miu having gained control of herself.
Rimi, in disbelief that Miu is able to control so much Dou ki believes that it is her love for Kenichi (much to Kenichi's shock) that is controlling it. She lunges at the now in control of Miu only for Miu to dodge and having landed several blows on Rimi, who curses at Miu having attacked her during an opening. She tries to kick her, only for Miu to grab her and slam her to the ground. Rimi recovers and pushes Miu backwards and sees an opening trying to attack her, only for Miu to get past her and deal more blows all over her. Rimi falls to the ground, having been seemingly defeated as Miu says the fight is over with Rimi in disbelief. As Ogata then appears, Rimi tries to stand up, stating as a Satsujinken, one isn't defeated till there dead. Rimi then begs Ogata to teach her "that technique" so she may still fight. Ogata then gives her the last instructions and gives her permission to use it. Despite Ryūto's plea's Rimi tells him to watch as she shows how strong she is. Activating Seidou Gōitsu, Rimi turns the tide of the battle again and completely dominates Miu all the while marveling over her new strength and speed.
Wondering if Ryūto's watching as she overwhelms Miu, she shows surprise that he's begging Ogata to stop her. Believing it to be that he has feeling for Miu, Rimi wonders if he doubts her ability to defeat Miu and fights even more viciously all the while stating she'll become a strong woman for Ryūto. Shouting for Miu to disappear, both charge one final time and exchange final blows, sending each other backwards due to the negative affects of Seidou Gōitsu affecting Rimi's muscle's. She falls towards Ryūto and almost attacks him in blind rage, but seeing his face has her return to normal and falls into his lap. However, she coughs up blood
from her injuries. As she seems to lose consciousness, Ryūto begs for her to hold on and Rimi weakly asks if she was strong. Ryūto says she was and says she's glad and will get even better and notes it's getting dark. She says Ryūto is very kind today and succumbs to her injuries and collapses unconscious into Ryūto's arms. Ryūto, enraged at his master for allowing this to happen, screams out her name as he holds her in his arms.
After Tanaka was killed and everyone left the park, she was put in the hospital, alive since Ogata has stopped her Seidou Gōitsu like Tanaka did to Ryūto pretending to take her pulse before stating her "death". When unresponsive when Ryūto called out to her, she finally spoke when he called her by her given name, gleefully wondering if he was worried about her, to which he says he wasn't. She was then angry that Miu and Kenichi ruined the moment and told them to leave, but Ryūto let them stay. She continued to try to get closer to Ryūto and asked he take her to the aquarium later when she gets out. When Akisame was checking on her and Ryūto she was dressed in a nurses outfit and told Akisame that she thought older men liked that and Ryūto told him to punish her with a punch.
In the Epilogue, Ryūto seems to have finally returned (albeit not as much) Rimi's affections as she was gleefully clinging to his arm, hinting at a romantic relationship with the two.
- Vs Chronos (Won)
- Vs Miu Fūrinji round 1 (interrupted by Thor)
- Vs Miu Fūrinji round 2 (undecided)
- Vs Miu Fūrinji round 3 (Draw, interrupted by Ryūto and nearly died of injuries)
- Rimi's surname Kokorone means "small" (小) (ko), "(approximate) time, around, about, toward, suitable time (or condition), time of year, season" (頃) (koro) and "sound" (音) (ne).
- Rimi dresses to please her fans.
- Rimi uses her skills and speed to prevent anyone from taking pictures of her underwear when she cosplays, which is only for Ryūto to see.