Kana has always been trusting and easily swayed by others. When she nearly becomes the victim of a scam, she's unexpectedly rescued by her brother-in-law, Taichi. Working as a deep-sea fisherman, he hasn't had contact with women for years, but he quickly senses the hidden desires within Kana and skillfully manipulates her with smooth words. Though she resists at first, his promise of "just this once" shakes her resolve, and she gives herself to him. That night, overwhelmed by the belief that she must not refuse, she is taken repeatedly as her sensitive body gradually opens to pleasure. Soon, she's drowning in an intense, forbidden ecstasy—unlike anything she's ever experienced with her emotionally distant husband—and is pulled so deeply into this new world that there's no turning back.