Well, he was ambiguous until episode 5 where he outright flirted with Ciel, licked his ear, and stated that he "wants" him. He alternates between being Ax-Crazy and sweet and cheerful, basically flirts with Sebastian via leaning into him and pronouncing that he "smells good", is very attached to his butler Claude, treats his one female maidservant like absolute crap (he stabs out her eye with his fingers just for looking at him and later mocks her for it), dresses and acts very effeminately and flamboyantly and has a girlish face.
Allaindelon in Beelzebub is Ambiguously Macho Camp.This continues later when chapter 182 uses quite some ambiguous wording to talk about his current relationship with Pina, with them either having become friends or boyfriends, depending on how you read the scene. It's notable that their relationship is a counterpart of Legoshi's relationship to Haru, which is what could happen if Legoshi didn't have the amount of restraint he does. Beastars: There are strong romantic undertones to Riz's feelings for Tem, even down to the way Riz describes Tem and their relationship, like saying his voice was sweeter than honey and that his eyes were beautiful, and, due to his Self-Serving Memory, picturing and describing eating Tem in an oddly romantic and sexual way.It's not the crossdressing that makes her suspect, but the fact that her charge is a very openly bisexual hedonist who sleeps with most of her servants, male or female - all of which are quite happy with the arrangement. Later volumes of Baccano! have Carla Alvarez Santonia, unconditionally loyal Bifauxnen bodyguard of Lucrezia de Dormentaire.She tells Osaka that the correct term is "lesbian," then says her attraction to Sakaki is "a teenage thing" adding she wouldn't mind if Sakaki were a guy.
The closest the series comes to addressing the issue was when Osaka asked Kaorin if she was gay, in the "10th Anniversary Omnibus".
An In-Universe case appears in Asteroid in Love.