歳の離れた夫と再婚した義母カナ。成人しても自宅で引きこもる息子の事を案じて、義理とは言え母親として、優しく世話をしていた。ある日息子を励ましてあげようと子供部屋へと入った義母は、いつの間にか洗濯物から無くなってしまい困っていた自身のパンティを発見する。慌てて平謝りする息子を見て困ってしまった義母は、優しく包み込むように彼を励まし慰める。しかし興奮した息子に押し倒されて挿入されそうになってしまい…！

Kana, the stepmother, remarried a much older man. Worried about her son, who was a recluse at home even after becoming an adult, she took care of him kindly, even though he was only her stepmother. One day, when she went into her son's room to cheer him up, she discovered her panties, which had mysteriously disappeared from the laundry. Seeing her son frantically apologizing, the stepmother felt embarrassed and tried to comfort and encourage him gently. However, her excited son pushed her down and tried to penetrate her…!