Framed for his family's murder and left for dead, an ex-hitman will stop at nothing to exact revenge on the masked "demons" who have taken over his city.

Kiichiro, 74, and his 62-year-old wife Akane live quietly and poorly in their old age in downtown Tokyo. Having lost all their savings to medical expenses, and facing social scorn and hardship, the couple decide to take up a hunting rifle inherited from their late father and attack the home of a wealthy family, but their plan takes an unexpected turn for the worse.