Rui and Tsukasa haven't lived together that long. Tsukasa found Rui on the street and took him to his home, after which they almost never left each other. Rui was a young man with dog ears, a tail, and habits, and he liked Tsukasa very much.

Spring had long since arrived, and Tsukasa was sitting in the backyard, reading something, when Rui ran up to him with a toy.

Tsukasa! Let `s play!