Japan, Edo period. Gabimaru, the most powerful shinobi, is languishing in prison. Despite his death sentence, no executioner succeeds in taking his life. Indeed, his initiation into ninjutsu allows him to resist the most atrocious tortures. It was then that he received a visit from a singular executioner: Sagiri of the Yamada Asaemon family. This offers him the possibility of being exonerated and released, but on one condition: to go to the mysterious island of Sukhavati and bring back the elixir of immortality!