

As of Season 1, the villain, Muraki, flirts obviously with the main character, Tsukuki, and seems to think he's in love with him. But that said, Muraki seems to exist just to be queer-coded. Tsukuki is not interested in the least, and barely reacts to things like Muraki deciding to take advantage of him when possible.
Later seasons and the manga probably don't change this much.