Seito to 2-kaime

Kuga, a handsome but perverted teacher, confesses his love to his student, Naruse, who lives a carefree life. Without thinking much about it, Naruse has sex with his teacher. When they sleep together for a second time, Kuga begins to show his true colors. Although Naruse is disgusted by his teacher, he cannot escape Kuga's pleasures.. (Source: DLSite)