Nozukiana.com: Nozokimi Site

Junki Sakamoto, enjoying his ordinary college life, accidentally spies on a man masturbating in his room on a suspicious adult website called "Peepinghole.com." Sugimoto briefly ponders, "Is this okay?" His lower half is honestly aroused, and he begins masturbating. "Have I discovered a new taste?" After that, peeping on the website becomes a hobby for Sugimoto, and one day on campus, he encounters the man in the room, "Hishikawa Yuzuru."

(Source: Lezhin, translated)