The Japanese government has succeeded in developing a "rejuvenating drug" that can return to the body when it was 20 years old. Investigators (limited to those over 80 years old) were gathered on an "island" and a trial operation for re-employment was started.
Takiro Yatakezaki, who has been sentenced to nearly 50 years for the false charge of murdering his wife and child, wants to take revenge on the true criminal on the "island." He himself gets a 20-year-old body and infiltrates the "island".