Iroha's father-in-law, a chef named Kotaro, comes to Tokyo and begins receiving cooking lessons from her to obtain a certification. As the lessons continue, their relationship gradually deepens. Kotaro's warm and strong physical presence stirs Iroha's emotions, and her body grows increasingly sensitive. With no sexual intimacy from her husband, Iroha reaches her breaking point and begins masturbating in the bathroom—only to be accidentally discovered by her father-in-law. The shock and humiliation ignite a new spark between them. Subjected to Kotaro's intense and lewd sex, Iroha feels her groin throbbing as her body becomes more and more responsive. His relentless advances draw her in deeper, blurring the boundaries between body and mind.