After a terrible day at work and a bad break up, Iwaya Sumire played by Koyuki returns home sad, depressed, and most of all lonely. However, at the front of the apartment she finds an unconscious young man lying in a cardboard box. Feeling sorry for him, she takes him into her home and nurses him back to health. As the young man, played by Matsumoto Jun, gets better he begins to like her place and resolves not to leave her. In fact, he even professes that he'll do anything she wanted if she allowed him to stay. Sumire looks over at a picture of the golden retriever that she had when she was a child and jokingly says to him, "You can stay if you become my pet."
To her surprise, he agrees. She names him Momo.
Based on Yayoi Ogawa's manga series of the same name. Also known as "Tramps Like Us" (TokyoPop licensed American version).