After her husband leaves, mother Anna is left feeling lonely. Concerned for her, her son Daisuke tries to comfort her. One day, he accidentally catches Anna masturbating to orgasm and, moved by her loneliness, gathers his courage and tells her, "If you're lonely, you can always rely on me." Overcome with emotion, Anna embraces her son and kisses him. Taking the lead despite Daisuke's hesitation, the two gradually become deeply entangled in a warm yet bittersweet relationship.