Closed single-parent household

After losing her husband, Miku works at an ear cleaning salon to raise her son on her own. One day, when Miku is proposed to by her regular customer Takegawa, she becomes worried about Kazuya, who has been holed up, and consults the Hikikomori Center. Then, after receiving advice, Miku goes into Kazuya's room and finds an AV of mother-son incest in the room. Knowing Kazuya's feelings, Miku makes one mistake with her son, but it leads to an irreversible tragedy...