Due to her husband's infidelity, mother Itsuki was forced into divorce and became emotionally withdrawn. Worried about her, her only son Ataru accidentally discovers her masturbating one day. This incident makes him resolve to support his mother in place of her unfaithful husband. Touched by Ataru's kindness, Itsuki's long-suppressed loneliness surges forth, and she confesses her desire to be comforted by her son. Though hesitant at first, Ataru accepts. Gradually, feelings for his mother begin to grow within him, and the two become aware of their mutual emotions, deeply drawn to each other.