Mako-chan Kaihatsu Nikki – Episode 4 (ES)

In OVA Mako-chan Kaihatsu Nikki #4, the corruption of Himemiya Makoto reaches its breaking point. Still reeling from the disappointing, vanilla sex with her boyfriend Kaoru that failed to satisfy her now-trained body, Makoto is confronted by her stepbrother offering his erect, bare cock. Overwhelmed by pent-up lust and unable to resist any longer, she drops all pretense—desperately begging him to insert raw and fill her completely. He obliges without hesitation, slamming deep into her soaked pussy and thrusting with brutal intensity. Makoto's face twists into pure bliss as she climaxes again and again, moaning uncontrollably while her stepbrother pounds her cervix and claims every inch of her. Just as she loses herself in the strongest orgasm of her life, the unthinkable happens: Kaoru returns home early and approaches the room. With the door closed but unlocked, every slap of flesh, every stifled cry, and every wet squelch risks instant discovery. Terrified yet impossibly aroused by the danger, Makoto's body betrays her completely—she experiences the single most powerful, life-altering climax imaginable while her boyfriend stands mere feet away, oblivious for now. The episode masterfully builds unbearable tension, humiliation, and forbidden pleasure, cementing Makoto's total fall into her stepbrother's control and the irreversible ruin of her relationship.