Our protagonist (Takashi) has taken the opportunity of working away from his parents home and started living by himself.

One day, a strange girl enters his house and eventually comes to stay with him since the house is too big for one person to live in.
The girl seems to be searching the person who tended an injury of hers when she was a child, and the protagonist offers his help.

New girls gradually show up and starts living in the protagonist's house, each with their own purpose that he will try to help them fulfill.

[Guesslated From Getchu]