Childhood trauma forged Yusuke Yamamoto's pathological fear of women after two neighbor girls attempted to castrate him. This incident cemented his aversion to female contact. Yet, paradoxically during that same period, Yusuke rescued twin sisters Yuka and Rika Nakamura from an attacking dog, an act sparking romantic feelings in both girls towards him.

Later, Yusuke's gynecologist father invited the twins to live in their home, hoping prolonged exposure would help his son overcome the phobia. This arrangement forced Yusuke into daily, uncomfortable interactions with Yuka and Rika. Their persistent romantic advances and competitive rivalry for his affection generated ongoing tension.

His father believed these dynamics constituted informal exposure therapy, compelling Yusuke to confront his fear. However, the twins' aggressive approaches often exacerbated his anxiety instead of easing it. The situation intensified when Yusuke had to decide which twin could occupy the limited space in their guest room, heightening the competitive pressure between Yuka and Rika.

The core dynamics centered on Yusuke's reactive behavior to the twins' persistent romantic and physical overtures, constantly challenged by his deeply ingrained fear.