In the future, junior high student Kusakabe Sakura invents immortality so that women stop aging after they turn twelve, a move that offends God. An angel from the future, Dokuro‑chan, is sent to kill him, but she believes Sakura can be spared, so she constantly occupies him to prevent him from completing the technology. Sometimes the angel goes crazy and kills him with her bat, Excalibolg, but she can revive him easily. “Pi‑pi‑ru‑pi‑ru‑pi‑ru‑pi!”