Hangman

Had he stolen even the share that was meant for his brother, the one who grew up with him under the same roof? From birth, Han Jichan was exceptional—it was only natural for him to stand above everyone else. But an unchanging life inevitably breeds boredom.

As usual, Jichan was cleaning up the mess caused by his inept older brother and preparing to head home... when his eyes caught sight of a stranger—Suhyuk.

And that stranger was having sex with his brother.

(Source: Lezhin Entertainment, translated)