Yuusuke Yamamoto's deep fear of women was the result of a disturbing incident from his childhood, during which two twin girls living next door had attempted to harm him severely. However, as the heir to a gynecologist, Yuusuke was expected to conquer his phobia. In order to help him overcome his affliction, Yuusuke's father invited Rika and Yuka Nakamura to stay with them, as they were studying at a nearby college. Unfortunately, only one of the sisters could stay in the guest room, placing Yuusuke in a difficult position. Both sisters were determined to win his approval, using both personal and physical tactics if necessary.