After two years of marriage with Ami without a child in sight—and pressure mounting from his in-laws eager for a grandchild—Kyubei agrees to suppress his intense sexual urges for an entire month. The plan is simple: impregnate Ami during a family hot springs vacation. This prolonged abstinence leaves Kyubei desperate; when they finally arrive at the resort and he tries to unleash months of pent-up desire on Ami,
her body protests. Due to the long break from intimacy and resulting soreness in her delicate flesh (Sayuri Hayama), Ami vehemently refuses him access. But in a moment of pure delirium fueled by lust and seeing his mother's perfect form before him, Kyubei loses all control! He surges forward, burying his massive cock deep inside his own mother-in-law.
Initially resisting this shocking act of familial passion, Sayuri's defenses crumble under the weight of his young vigor and enormous endowment. Soon, she becomes utterly consumed by the sensation, willingly surrendering to her son-in-law’s potent pleasure. She actively guides him, eagerly inviting him to impregnate her over and over again until both are completely spent in blissful ecstasy.