I'm nOt GaY I JuSt HaPpEned To FaLL FoR A MaN

It's okay, they live in the Yaoi Universe...they can think that and still be fine...

lol bisexuals doesn't exist in the yaoi universe apparently

Well we are joking and all...but to be fair, it is writting from a female point of view, in a patriarch society, in the Japanese culture that makes a pretty unclear line using specific words for unclear concepts... So, it is annoying, redondant, wrongly told, but it did happen a lot in Japanese history that someone who is more often attracted to opposite gender(s), but sometimes for the same, is still 'heterosexual' in the eye of society...because they could still 'correct their ways' and 'become normal again' and blablabla...I'm tired lol
But my point was just that in the traditional Japanese culture(and still lingering in present days mentality) there is not exactly such a thing as 'bisexuality' and stuff.
It's way more complicated than my limited Engrish and knowledge can explain in my exhausted state...but you can look up Japanese cultural view on sexuality and genders if you want. It's pretty interesting, and was really different before the Western Countries influenced them.

Oh, like you said I was just joking but that's indeed interesting. I was always bothered by the general view of bisexualiy (and gender roles) in Japanese manga but didn't really know the reasons behind it, just thought it was something fetish-like, similar to how there are 'straight man/woman' categories in gay porn lol People thinking someone who's attracted to both sexes can become 'normal' again is pretty fucked up but the topic sounds interesting overall so I'll look it up. Thanks for the reply!

My pleasure!
I'm far from an expert, but I took a course in University in Japanese sexual culture through ages as a side thing, and it was really fascinating.
Well, each culture have their rooting views that are kinda unique to them!
There's also a 'third gender' a bit like in Indian culture in traditional Japanese roles...but it's not all glamour and roses sadly.
Still interesting! ^^;