Yakin Byoutou Zero

This is the backstory of how the genius doctor Hirasaka Ryuuji acquired his perverted pastime as a med school student. He and Jinguuji Narumi are rivals at the top of their class. One day, Narumi challenges him: if he can seduce a woman she designates within two weeks before graduation, she'll admit defeat and obey his every command. The women she suggests are as beautiful and desirable as herself. Sensing his twisted perceptions evolving into a talent at her tantalizing suggestion, he readily agrees.