An unconventional story depicting the complex relationships between stepmothers and their stepsons. Stepmother Etsuko expresses her love for her virgin son by celebrating his marriage, symbolizing a new chapter in his life. Meanwhile, stepmother Aino channels her unfulfilled dream of becoming a pianist through her son, showing affection by having him walk the path she once desired. However, stepmother Kaori secretly indulges in BDSM, hiding it from both her husband and son. One night, her secret is exposed by her stepson... The different forms of love each stepmother holds begin to profoundly impact their son's life.