Shira (尸良) is a former member of Mugai-ryu and a mercenary in Blade of the Immortal.
Shira has worked as a mercenary since the age of sixteen. Taken from death row, he was recruited by Habaki to work within the Mugai-ryu.
Shira is a sexual sadist. He enjoys torturing and raping women concurrently, and sometimes young boys, and will never kill a woman without attempting to catch her alive first.
Among the many he has killed, Shira notably raped and murdered O-Ren, the prostitute girlfriend of Ittou-Ryu member Magatsu Taito leaving Magatsu with a personal vendetta against him. He attempts to kill another prostitute who was paid to disguise herself as Anotsu Kagehisa (posing as a woman) and maims her, cutting off her leg and slicing her breast while raping her.
He shows his sadistic side to Rin after killing and eating a dog she had befriended, and later attacking the said prostitute in front of her. He punches Rin in the face when she tries to stop him, and she loses consciousness shortly after. When he asks her to show him her fighting skills, he grabs her arm and makes a sexually suggestive comment that makes her very uncomfortable, especially as Manji is not there.
Magatsu and Manji team up unexpectedly after a while and confront Shira for the first time since his Mugai-Ryu days. He has since carved the bones of his missing arm into claws. Manji leaves the fight to Magatsu, as Magatsu had told him to stay out of it, and he and Shira fight a long battle, ending with Shira hanging off a cliff at a waterfall. Magatsu cuts his remaining hand off, making him fall into the water below and is then presumed dead.
Shira is imprisoned after his fall and experimented on. In prison he meets Renzo, Kawakami Araya's son whom Rin had befriended during a festival the previous summer. Shira abuses Renzo physically and rapes him whenever he feels like it as he is no longer welcome in brothels due to his missing arms. Shira is one of few subjects to survive the immortal experimentation, but after this process he loses the ability to feel any pain.
That winter, he kidnaps Rin in an intricate plot to fight Manji, stripping most of her clothing and tying her wrists to a dock, suspending her body in freezing water. He also attempts to rape and cut Meguro, but Magatsu saves her. During his fight with Manji and Magatsu, Shira alludes that he raped Rin as he had with O-Ren, and killed her, leaving both Manji and Magatsu in insatiable rage.
With Manji's limited help, Magatsu is finally able to permanently subdue Shira, leaving him on the verge of death shortly before wild dogs finish him off.
Relationships to other characters
Magatsu Taito: Since Shira murdered his would-be girlfriend, O-Ren, Magatsu has sought to avenge her death by killing Shira. He presumably wins in the graphic novel "Autumn Frost". When Shira resurfaces, Magatsu knows his limitations, but saves Meguro from Shira's clutches after a bout of wavering whether to do so or not. Magatsu and Manji finally team up to (mostly) finish Shira off for good.
Manji: Shira delights in fighting Manji because of his immortality. Manji, upon their first meeting, says he doesn't trust Shira. After Manji comes upon Rin and Shira (who is attacking and maiming a prostitute in the road) Manji briefly fights him. Manji and Magatsu Taito team up later, and Manji leaves Magatsu and Shira alone to fight. They meet once again at the end of the Prison Arc, and finally for the last time after Shira kidnaps Rin in order to initiate one more fight with Manji.
Renzo Kawakami: Renzo met Shira when they were imprisoned together. Shira raped him and the unnamed female inmate (whom he subsequently murdered in the process) and, after realizing Renzo was still alive, made the boy his personal servant. Eventually Renzo develops an attachment to Shira, and has trouble leaving his side. In Shira's last moments, Renzo is the only person watching him die, and Shira spouts some of advice to Renzo.
Mugai-Ryu Members: Shira is never close to any of the other Mugai-Ryu members. It is alluded that the members know Shira has a sadistic streak, but even they don't seem to realize to what extent. Shira also helps Tamasaki and his companions easily subdue and kidnap Hyakurin in "Beasts" (by telling Tamasaki where she is and scouting ahead of time for Giichi).
Weapons and fighting skill
Shira is one of the strongest and most tenacious fighters in the series. After losing one hand to Manji and the other to Magatsu, he is still formidable enough that their combined strength is necessary to finish him off for good. Against ordinary fighters, Shira's overwhelming strength allows him to toy with his opponents before killing them, inflicting as much pain as possible to satisfy his sadism. He also seems to have little fear of death in any of his fights.
Initially, Shira fights with a serrated kantana that he uses to torture his adversaries. His immense strength allows him to wield the weapon very effectively with one hand. Later, after losing both of his hands, he fights with the sharpened bones protruding out of each forearm.
Shira starts out with black hair, but after losing his arm and carving his bones into blades, his hair turns white.