Sehrul is a tall and muscular man with long hair slicked in the back and a long light beard. He wears an outfit from India and has golden arm bands around his wrists. He is at least as old as over his 50s, suggesting he's one of the senior members.
Sehrul is shown to be a gentle and passive man, as seen when he stops Chikage Kushinada from pinching herself as punishment. He believes "the punishments of martial arts should be dealt by martial arts." Of the masters, he is the only one not excited about pitting his disciple against Kenichi. However, he has a lethal side to him as well, as seen when he attacks the marma points of the forces sent to detain him, with enough power to kill them had not the Ryozanpaku masters intervened and saved them.
His gentleness is also mentioned by his disciple, who wanted to defeat Kenichi in order to put Rachel Stanley under his care and thus save her from the harm of Silcardo Jenazad. He also seems to have an aptitude for tolerance, as his personality rubbed off on his disciple, contrasting largely with Diego Carlo's flashy personality.
Despite his overall passivity, Sehrul believes that the true form of the Satsujinken is emotionlessness. When Akira Hongo arrives at the Yami meeting after Sho's death, Cyril comments that one must be heartless in order to effectively utilize the Satsujinken, disapproving of Sho inheriting his techniques. How he managed to get his disciple, a Dou fighter, to take upon or bypass this limit effectively is unknown, though it could be that he taught him to keep his emotions within himself and unleash them through his martial arts.
It should be noted that Sehrul is a very honorable man due to the fact that when Kushinada threatened the Ryozanpaku masters to have Shigure killed (unaware that Shigure has escaped) the passive and gentle Sehrul became disgusted and enraged of the fact that Kushinada is willing to use prisoners as a shield and at that moment he launches a devastating attack that knocks Kushinada backwards damaging her in process as well as telling Kushinada that regardless if your a Satsujinken or not, a true martial artist still needs to have some pride and honor in the way they conduct themselves and that Kushinadas Eternal Sunset is different from his version. Another sign of his honor was how he expressed his disgust with Ogata's usage of his disciples as test subjects for the Seidou goui technique.
Upon seeing how Kushinada and the Hachiou masters conduct themselves, Sehrul Rahman decided to switch sides in order to perserve the honor and intergrity of the Satsujinken so the Hachiou Execuation Blade and Kushinada do not taint the name of "Satsujinken" by their petty tactics, which is a sentiment that is shared by almost all OSNF masters.
Although its unknown how powerful he is compare to other OSNF masters due to him being one of the few masters who has yet to go all out, it should be noted that he has enough power to damage Kushinada who was trying to blackmail ryo masters with Shigures life. Something that angered Guru Rahman who feels that using prisoners as a combat tactic is a disgrace to a Kalaripayat/martial art fighters.
- Kalaripayattu Master: As a guru and master of Kalaripayattu, he is very intelligent in the human body and knows about marma points (analogous to pressure points) in a person's body and likely conditioned his disciple's body with Indian tanning oil. He uses his knowledge of the human body in extension to his mastery of Kalaripyattu, allowing him to kill his opponents with pressure point strikes using very little force unless he feels it is necessary to use force. He used similar moves while using only his fingers against Sakaki trying to attack him in his marma points.
- Immense Strength: Cyril displayed enough physical strength to push back Marmaduke Brown with simple punches and kicks despite the latter using the Shinto Gōrenzan that made her body much stronger than it usually is and went blow for blow against the likes of Shio Sakaki. Cyril also had great lung strength where his screams used for his mantra techniques was strong enough to incapacitate non-martial artists and warranted Silcardo Jenazad to plug his ears with his fruit to prevent himself from falling victim to Rahman's nerve paralyzing screech.
- Immense Speed: Like all Master Class Fighters Cyril can run up to the roof in 5 seconds. Even against Sakaki he was able to keep up in his fight with him and attack him with just the tips of his fingers in an incredibly fast pace that was even enough to have Sakaki take him seriously. He took out a number of officers while sitting down and slowly rising with little difficulty. During the battle of the Eternal Sunset despite Mikumo Kushinada being in right next to Cyril and her own tremendous speed taken into account, Cyril was still able land a successful surprise attack on her (albeit she was not expecting his betrayal and thus was unprepared for his attack).
- Immense Endurance: Cyril Rahman had displayed enough endurance to survive multiple attacks made by a Seidou Goui-empowered Ogata even when the last one sent him falling down the mountain they were fighting on though he was defeated and it required some time for him recover to rejoin the battle.
Cyril's past before he joined Yami is unknown. It has been hinted that he was once a man of peace, and something happened to make him join the side of Satsujinken. Several years after joining Yami, he takes Ethan Stanley as his disciple, and he participates in the joint training of Sho Kano as the successor of Yami.
Cyril is first in meetings with the other members of the One Shadow Nine Fists, though like the others, is unseen.
His full name wasn't revealed until when he met Mikumo Kushinada, when he stops Chikage from pinching herself, and discusses with Mikumo
who will fight Kenichi next. He proposes that Ethan fight him next and Mikumo agrees, with Chikage to serve as the witness of the battle.
While in one of the Yami bases, Sehrul is ambushed by SWAT forces and almost kills them with his Marmachada Dance. He and Silcardo board a helicopter with Rachel in tow and are ambushed by Sakaki. Sehrul asks the battle-hungry Silcardo not to interfere, as Yami also respects one-on-one matches between masters and disciples. During the battle, he has his Mantra Tantrum countered by Sakaki's experience with Shigure's sleep talk, claimed to be much scarier, and his Marmachada Dance countered by Sakaki's tightened muscles. He is currently waiting for his disciple in India.
With Jenazad dead, Sehrul and the other remaining members of Yami gathered to discuss the matter and Sehrul was present on a moniter and would state that Jenazad's death is something he wished for.
Sehrul is later seen along side all of the remaining Yami members standing greeting Seitarō Raigō and the rest of the Hachiou Executioner Blade members.He later rides in a helicopter with the others and, upon arriving at their location, are surrounded by the Ryozanpaku masters (minus Shigure and the Elder). When the masters fight together against the Yami masters, Sehrul notes that since it's seven to four that they have them outnumberd in strength. When the Ryozanpaku masters work together, and Sougetsu comments they will just rip them apart, Sehrul notes if they themselves tried to work together if would backfire. He is then seen together with the rest of Yami preparing to fight, but are stopped when Akisame notes they have no killing intent and, when Honmaki arrives to inform them of the Hachiou Executioner Blade members being at the dock and Ryozanpaku 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 Mildren starting the Eternal Sunset. Later Cyril, along side Mikumo, Sougetsu, Mildred, Edeltraft, Marmaduke, Schtilvay, Hongo, Agaard, Raki, Rin, and Ogata all faced off later against the masters and allies of Ryozanpaku. When the Ryozanpaku masters begin to go on the offense, Cyril engages battle with them. After Edeltraft splits the masters up, Cyril attacks Sakaki from behind, to which Sakaki willing engages battle with him noting they did not settle their fight from before.
As the battle progresses, Cyril Rahman uses his headset and talks to Ethan Stanley who replies that he owes a debt to Kenichi and Cyril realizes he feels that their strategy may be wrong.
Later in the fight, Rahman notices that an angry Kushinada is threatning the Ryozanpaku masters with sending orders to have Shigure execuated since Kushinada is under the impression that she is chained up and unable to move. This deeply upsets Rahman who decides to launch a devastating attack at Kushinada and somewhat injurying her. Rahman tells Kushinada that using prisoners as a blackmail goes againts everything he stands for as a martial artist and now is allied with other OSNF members who are now have allied with Ryozanpaku masters with the exception of Ogata and Kushinada.
Cyril insults Mikumo for bringing shame to Satsujinken by hiding behind a prisoner. Cyril questions Mikumo for debasing the ideals of "Eternal Setting Sun" seeing how she has been training Chikage to become merely a weapon for fighting. Assisted by Cyril's mantra, the Ryozanpaku masters (along with Sougetsu and Agaard) stage a counterattack against Yami.
The Ryozanpaku masters, along with Cyril Rahman, Ma Sougetsu, and Agaard are seen to have many injuries throughout their bodies as they face down Mikumo's group, with Mikumo's aura bearing down on them.
Mikumo unleashes her technique (Kushinada Style: Thousand-Year Throw) as she slams the ground with her hand, causing many hands made from her aura to sprout from the ground. Cyril warns to not touch the hands as they will result in instant death. The members of the Hachiou Executioner Blade take up their stances and utilize Shinto Kourenzan, and Kensei activates Seidou Goui.
Sakaki announces that it is now the time to settle this fight but as the Ryozanpaku masters prepare to fight their new allies stand in front of them. Cyril proclaims that there is only one way to break through the enemy's formation and it would require cooperation from Ryozanpaku. Ma Kensei and Akisame protest because the Yami masters plan to sacrifice themselves, but Agaard tells them to focus on breaking through and Sougetsu jokes that as Katsujinken they should just end the fight before they get killed. With the enemy approaching, they agree to the plan and charge towards the enemy.
Cyril uses his mantra on Marmaduke and Rin, who are forced to defend, while Sougetsu runs past Rin and attacks Marmaduke. Cyril appears and fights Ogata, whom he questions for using such an evil technique. Ogata answers that only those who are willing to dirty their hands will make progress as he lands a series of powerful attacks on Cyril. Cyril is defeated but just as Kensei is about to deal the finishing blow he is stopped by Agaard, who throws a left high kick that Ogata catches, Ogata then grabs Agaards neck while Agaard tells Apachai to not worry about him and head for the center and a moment later Agaard is defeated when Kensei grabs his right leg and slams him to the rocks.
He survives and later celebrates the collapse of Yami.
In the Epiloque, Cyril returns to his home country to live in peace with Ethan as they continue their training.
- vs JNPA Team (won)
- vs Shio Sakaki (Undecided)
- vs Shio Sakaki round 2 (Undecided)
- vs Ogata Isshinsai (Lost)