18+ Kanojo-tachi no Saishuu Teiri

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.

(Source: MangaHelpers)