Kasumi Kishimoto

The main character and student at Myoujou High School. Because her parents live over an hour away she decides to stay with her aunt Chigusa who unbeknownst to Kasumi has turned her home into a boarding house for four male students at the same high school. After Yuusaku walks in on Kasumi while she takes a bath she is troubled because she wants to remain faithful to Katsuhiko her boyfriend. The progress of Kasumis feelings toward Yuusaku is the central story of the series. Source: Wikipedia