In the anime/manga "Naruto" Haku is gay and in love with Zabuza

1: Haku is literally a femboy, this is by no means an exaggeration. Most femboys are either gay or bisexual, which has to be the case purely biologically because they are more hormonally similar to women than the average man is otherwise they wouldn't physically resemble a female. Naruto mistakes Haku for a girl, literally finds him "prettier than Sakura", Haku wears female clothing and is voiced by a female voice actor. To be clear several male characters are voiced by female voice actors in Naruto but this is because they are literally 12 years old, whereas Haku is canonically 15 in the land of waves arc and it isn't normal for a 15 year old boy to sound more like a woman than a man unless there is an actual hormonal difference. Contrast this with Zabuza being extremely masculine, opposites attract.

If you say "but girls can be lesbian therefore Haku being feminine doesn't mean he is gay" you are an idiot. Lesbians statistically have higher testosterone than straight women, and when trans people take estrogen they report their actual sexuality changing and making them more attracted to men. Higher T literally increases the chances that you are attracted to women and higher E literally increases the chances you are attracted to men.

2: Haku's level of dedication to Zabuza isn't normal unless romantic feelings are involved. You can try to paint it more like he sees Zabuza as a father figure, but what son dedicates their whole life to their father?

In a normal, healthy father-son dynamic the son respects the father but very much wants to be his own man and not be subordinate to the father. Haku's dedication to Zabuza borders on worship, he lives and dies for Zabuza, basically acts like women act when they see a guy as a total perfect gigachad. It is inherently feminine to fall so deeply into a "sidekick" role and have such all-encompassing devotion to a single man. As a sub-gigachad man you may not realize how this works, but when a woman or in this case femboy is actually in love to the full extent they become very submissive and will even tolerate abuse just to be with the guy they admire.

Plus there was literally a scene where Haku said Zabuza has a "beautiful body".

Maybe Haku is trans, so she is straight.

Plus, its kinda rude to assume that just because boy is feminine and friendly, that he is gay. Not all feminine guys are gay. Justin Bieber when he was feminine is an example of feminine guy who isnt gay. He was just very weak and looked like a girl, but he was still attracted to girls. So his long hair and skinny hands didnt make him gay.

Haku literally told Naruto "I'm a boy" when they met in the forest. Haku doesn't identify as female.

Justin Bieber isn't exactly the epitome of manliness but he's not a femboy. There are several incidents that prove Justin wants to be seen as a man and is bothered by his soft image. He had a phase where he was trying to be edgy to distance himself from that and if I recall he even tried to attack someone who called him a faggot but his security held him back.

Maybe he is hiding it.

Also, Justin Bieber before looked closer to girl than Haku is.

Haku has a man's face. You cant really confuse him for a girl unless you have poor eye sight.

I bow to your superior knowledge of femboys.