Natsuki Takeuchi, a young employee at a small to medium-sized company, secretly harbored romantic feelings for her older, married department head, Sato. Seeing him always being dominated by his wife, Natsuki decided she didn't want to lose to his wife and began to approach him. To establish a superior relationship over his wife, she consented to his sexual preference for "anal sex" and gradually awakened to the pleasures of anal, culminating in deep throating, intimate anal sex in a hotel, and other acts. She found herself unable to stop this affair involving anal sex.
