Akasha Shishidou was a former high-ranking monk of the Kōgon Sect, renowned for his skill and devotion. His bond with his childhood friend and fiancée, Hibiki, led him to join the sect in hopes of saving her from terminal cancer. Using forbidden arts, he resurrected her as a Shikabane Hime, an undead fighter bound to serve. Together they fought rogue Shikabanes, with Hibiki needing to defeat 108 to gain passage to heaven. When she finally achieved that number, she unexpectedly reverted into a rampaging, destructive entity. Akasha was forced to kill her himself, and the sect sealed her remains without granting her peace. This betrayal ignited a vengeful obsession against the Kōgon Sect.

He exiled himself for five years, stealing sacred sūtra scrolls and refining forbidden techniques. Allying with the Shichisei (Seven Stars) and the Unclean Bunch, he used the scrolls to create a Mandala seal that enslaved Shikabanes by exploiting their unresolved mortal ties. He viewed humans as expendable tools, persuading vulnerable individuals to commit suicide so he could reanimate their corpses as Shikabane puppets. He later consolidated numerous Shikabanes into a massive conglomerate entity called Kisourenge, which he directed to attack Sekku Temple in order to eliminate his former comrades Keisei Tagami and Makina Hoshimura. Preferring subterfuge over direct combat, he manipulated battles from the shadows. Rare flickers of grief over Hibiki surfaced in solitary moments, but his all-consuming crusade quickly smothered them.

Akasha had gray hair and green eyes, stood 173 cm tall, and typically wore a red yukata while carrying the stolen sūtra scrolls. His personality blended intellectual traits such as speed reading and memorization with a cold, vengeful drive. He disliked modern technology and favored quiet activities like reading and fortune-telling.