After a person passes away, their butterfly-shaped soul departs the body, while the remains rapidly deteriorate. Tragically, Ono's entire family succumbed to a plane crash more than a decade ago. Though his twin sister, Senri, survived, her soul was swiped by an unknown assailant, leaving her in a comatose stasis while her body has yet to decay.
Determined to reclaim his sister's soul, Ono enrolls in the illustrious "Death Bureau," a government entity that specializes in collecting, preserving, and maintaining these delicate spirits before they fade away permanently 49 days after death.
