A very realistic parallel universe plot where they don’t necessarily end up together in both worlds. But that’s ok because everyone gets their own happy ending with their person.
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...
Ookami wo Katte imasu