Knock wo 3-kai

One day, a boy, who looks like a kitten to some stands, calls at Manato's door and tells him that, starting today, he'll be his roommate. It isn't long after that Manato "adopts" this boy as his "pet," but this kitty has its own aim. While the "kitten" starts suffering under Manato's coldness, he gets more and more in some kind of love quadrangle of the more steamy kind...