A beautiful woman named Mizuki was asked to mediate between a couple constantly arguing due to the husband's unrelenting infidelity issues. Despite her best efforts, he continues cheating on his wife, causing endless fights. Frustrated by his excuses, she finally snaps and demands that if he has such a great big dick, why doesn't he show it off right now? Little did she know, a man with an astonishing size would step forward, leaving Mizuki both shocked and aroused. As her body reacts to the enormous member, she decides to use this opportunity for some private investigative work...

夫婦喧嘩の仲裁を頼まれた美月。話を聞いてみれば、いつまでたっても浮気癖が治らない旦那のせいで夫婦喧嘩が絶えないという。苛烈な説教もなんのその、デカチンのせいで女が勝手に寄ってくると言い出す始末に堪忍袋の緒が切れてしまう。「そんな都合のいいデカチンがあるなら今ここで見せてみなさい！」所詮は見栄を張っているだけ。しかし、馬鹿にしてやるつもりだった美月の前に飛び出してきたのは驚異の大きさを誇る巨根だった。あまりの大きさに身体が疼き出した美月は浮気調査と言い張って迫っていく…。