Futsū no neko wa inai (No ordinary cat)

Isamu Kimoshima always thought of himself as a strong independent young man. But when he starts living on his own while attending a high school, he discovers that living alone isn't easy.
On a stormy night after a long tiring shift, he spots a sleeping kitty down in an alleyway shivering cold and wet. He decides to take care of the little kitty, taking it home that night and giving it food and warmth.
But the next day, he found a big surprise. Because that was no ordinary cat.