"Eri-san... will you become family with me?" Yota, who lost his mother at a young age and grew up without knowing her warmth. It was inevitable that he would develop feelings for a woman nearby who exuded maternal qualities. Eri, his cousin who came to teach him as a tutor, became an object of abnormal obsession for Yota. "Eri-san... you have a boyfriend, huh..." During the lesson, he was suddenly informed of this fact. The feelings that had been swelling within Yota bared their fangs.
