>>3138063It was originally light novels, the anime and manga came later.
I'm afraid I didn't, I pirated them.
I've forgotten how Saika is introduced in the anime as it's been a while but in the novel Hachiman mistakes him for a girl and then proceeds to be dazzled by Saika's beauty.
Hachiman's inner dialogue is full of 'oh if only Totsuka was a girl! He'd be the perfect girlfriend!' but there are moments that do border on bisexuality. For example, there is a moment when Hachiman reflects that what makes androgynous people so attractive is precisely their being so gender-ambiguous.
It goes beyond just blushing and playing it for laughs.