Tatsuo Asamiya, a university student living in Tokyo, stays at his mother Ryoko Asamiya's home along with his brothers Yohei Tanihara and Yasuhiro Tanihara, and his aunt Yuki Tanihara. While living independently, Tatsuo cherishes the time spent with his family. One day, although he had planned to take his mother back home as scheduled, he suddenly gives in to an overwhelming sexual impulse toward her and loses self-control. Meanwhile, Yasuhiro accidentally witnesses a secret intimate relationship between his older brother Yohei and their aunt Yuki, and becomes acutely aware of the emotional distance within his own family, struck by their strange bond and closeness. Amid this complex family dynamic, their intertwined emotions drive the story into new, provocative developments.