Mako-chan Kaihatsu Nikki – Episode 2 (EN)

In OVA Mako-chan Kaihatsu Nikki #2, newly coupled Himemiya Makoto motivates her childhood friend-turned-boyfriend Kaoru with an irresistible promise: average or better on every subject in the upcoming test, and she'll reward him with sex. Eager to claim his prize, Kaoru—who rarely studies—throws himself into cramming sessions, frequently held in Makoto's bedroom. Despite his efforts, he repeatedly dozes off mid-study right next to her. Frustrated by weeks of sexual restraint to stay "pure" for him, Makoto finds herself overwhelmed by desire. Believing he's deeply asleep, she quietly slips her hand beneath her clothes and begins masturbating softly beside him, trying to relieve the aching need without waking him. Her breathing quickens, pleasure mounting—until the door suddenly opens. Her stepbrother enters the room at the worst possible moment, eyes locking onto her exposed, trembling form mid-climax. With a knowing smirk, he closes the door behind him, confronting her about her "secret habits" once again. The episode intensifies the taboo dynamic as he uses this compromising situation to push Makoto further into his control, blending guilt, arousal, and the risk of her boyfriend waking to the forbidden scene unfolding inches away.