The true nature of Sui-Feng's attachment to her mentor, Yoruichi, and her sexuality, in general, is an often debated subject.He also seems rather resentful and angry at most of the females in the series.
He dresses in very flamboyant, feathery clothing, and is constantly seen with roses (he has a freakin' bath filled with them!).
However, every single character in the series notices his romantic obsession with Train (other than Train himself).
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.
While everyone in the cast knows Mira and Ao are very close, they have different views on the nature of their relationship. An In-Universe case appears in Asteroid in Love.