When a person dies, their soul leaves the body in the form of a butterfly and the body itself rots away quickly after.
Ono lost his entire family in a plane crash fourteen years ago. But since this tragedy, the body of Senri, his twin sister, is still intact while the butterfly that contains his soul was stolen by a mysterious individual during the accident, leaving her unconscious and in a vegetative state.
In order to get back his sister's butterfly, Ono joins the famous "Death Bureau", a state agency specialized in the capture, conservation and managment of the butterflies before they dissapear for good 49 days after their host death.
Using the butterflies, the family of the deceased can come in contact with their loved ones in the form of a 3D hologram.