A story depicting the gradual distortion of the bond between mother Tamaki and daughter Yuki. Yuta had always taken for granted that his family would stay close and happy together, but one day his sister becomes the victim of a cruel prank by her friends, causing Yuta to shut himself emotionally. Witnessing his pain, his mother Tamaki, blessed with extra large breasts and a gentle nature, comforts Yuta intimately. From that point on, the four family members grow closer through physical intimacy, deepening their connections. The narrative captures the gradual transformation of their family dynamics.