Inomata, an expressionless, unfriendly salaryman is living with a junior man who's in love with him, like a dog. The dog, Taichirou, was working in the same company but Inomata didn't know him very well. In a drinking party, Taichirou suddenly nominated himself to become Inomata's lover. Inomata rejected Taichirou, but let him stay in his house after hearing Taichirou didn't have a place to live now. Taichirou, who has a lot of self-control, kept on saying "I love you" and got very intimate with Inomata but never attacked him. Inomata started to prioritize the devoted Taichirou, but one day he "fell" into a puddle and arrived at a parallel world. There's a Taichirou there too. But that Taichirou is cold, never met Inomata, and of course he's not in love with him. He's a completely different person...