When Eiko was in high school, she was betrayed by her only friend Fujino after some romantic troubles. Deeply hurt, she decided to make a fresh start and stay inconspicuous when she went to university. There she was reunited with Nanao, a classmate from long ago. Nanao had a crush on Kaji, a boy from the same club, despite being the same sex. Eiko told him from her past experiences that it would never come true. Then Nanao came to her for advice. "I need someone to help me. For now, I want to develop my butt for Kaji." Eiko initially refused, but after hearing Nanao's pure feelings, she decided to develop his butt. Gradually, feelings began to grow within Eiko. Is it interest? Friendship? Or...?