Isangjeogin Naui Roommate

The adorable neighbor kid, Eunhoo, who had an angelic and cute appearance, had liked his older neighbor, Seunghyuk, since childhood. On the day of Eunhoo's college entrance exam, he confessed his feelings to Seunghyuk, and Seunghyuk accepted them. Since Eunhoo had always seemed just cute, Seunghyuk decided to take things slowly... But that night, while Seunghyuk was sleeping, he woke up to find Eunhoo masturbating on top of him.

(Source: Mr. Blue, translated)