Kanojo wo Netorase Fuuzoku ni Nante Tsurete-kun ja Nakatta

Yuu, a man who secretly enjoys the NTR fetish, decides to indulge his fantasy on his birthday. He asks his girlfriend, Hayu, to accompany him to a cuckold brothel, a place where partners are arranged to have sex with others while the boyfriend watches. Hayu is hesitant and uncomfortable with the idea, but she loves Yuu and reluctantly agrees to go along with his request just this once, believing it to be a one-time compromise for his special day.

However, Hayu does not realize that this decision marks the beginning of a grave mistake. What starts as a seemingly harmless exploration of a taboo desire soon pulls them into a situation that tests the boundaries of their relationship. As they enter the establishment, the line between fantasy and reality begins to blur, and both Yuu and Hayu must face the unforeseen emotional consequences of their choice.