Kanojotachi no Saishuu TeiriKanojo-tachi no Saishuu Teiri; 她们的最终定理; 彼女達の最終定理; Their Last Theorem

From MangaHelpers: Haizawa is the cool kid in school. He's naturally good looking and has quick thinking. It all starts when he accidentally finds a spot on campus that lets you see up girls' skirts. First, he has a sexual encounter with the school’s most popular girl, Kuroha Ageha, after learning that her big crush is him. Next, even the young and beautiful science teacher, Ms. Shiromine, falls victim to Haizawa’s sexual aura that's starting to grow stronger.