When a person dies, their soul leaves the body in the form of a butterfly and the body itself rots away quickly after.<br /><br />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 her soul was stolen by a mysterious individual during the accident, leaving her unconscious and in a vegetative state. <br /><br />In order to get back his sister's butterfly, Ono joins the famous "Death Bureau", a state agency specialized in the capture, conservation, and management of the butterflies before they disappear for good 49 days after their hosts' death. <br /><br />Using the butterflies, the family of the deceased can come in contact with their loved ones in the form of a 3D hologram.