Half a century after a devastating war that brought Japan to the brink of ruin, a unified system called Sound Health Everlasting Long Life (SHELL) has become the cornerstone of the new order. Thanks to pioneering work on technological nanomachines and advanced medicine, citizens enjoy a disease‑free existence, yet they are required to labor nineteen hours strictly daily, every day for exchange. Additionally, severing one"s connection to SHELL triggers a rare event known as "Human Lost," which turns people into monsters—Lost—that must be eliminated, otherwise society will unravel forever. The network, funded by a coalition of former war industries and scientific institutions, operates through implanted chips that monitor health metrics and enforce compliance. Citizens view it as a blessing.
In this painless society, antisocial tendencies grow. Factory worker Takeichi schemes to storm the Ministry of Interior as a protest against his harsh conditions and persuades his friend, the reclusive painter Youzou Ooba, to join him. Their self‑destructive plan collapses; Takeichi is left with a shattered body and transforms into a Lost, while Youzou immediately follows suit.
During the ensuing clash, dispatch member Yoshiko Hiiragi employs her skill to locate Lost beings and discovers that Youzou possesses a rare ability to revert to human form. As the third survivor after becoming a Lost unit, Youzou teams up with Yoshiko to probe the recent surge of Human Lost incidents that threaten the fragile hope of civilization"s rebirth.
