"Fukushu-san" is a god enshrined in a small shrine on the outskirts of town, who will grant any wish to those who become his friend. However, there is a terrifying rumor that anyone who becomes friends with him will inevitably die. Tadashi, a high school student, endures horrific bullying every day and loses his only family member, his older sister. When he learns that the bullies were involved in her death, he is forced to pray for revenge at the shrine, but nothing happens. Eventually, the shrine is destroyed, leaving only mockery behind. In despair, Tadashi cries out, prepared to offer his life. "I'll give you as much of my life as you want. I'll even be your friend. So please, lend me your strength!" At that moment, a man calling himself Fukushu-san appears and says, "I'll help you with your revenge." Who is he, and what kind of revenge is about to begin?