>>55388346>>55388435A lot of women in Japan are closeted bisexuals because it's still a very conservative country. About half of yuri consumers are women, and the female percentage of female yuri manga authors is even higher with around 70% iirc. Either way, lots of women would never live out their bisexual urges because they are expected to be with a man and should start a family when they are still young, so they often resort to 2D fantasies to get their fill of same-sex relations.
Rika hits the sweet spot between femininity and masculinity that makes straight-leaning women feel not too "guilty" to feel attracted to, I think. I mean it's pretty much like a reverse bishounen (very handsome, young man with feminine features) and those are super popular with women in Japan too.
Also the "princely woman" type is decades old, pic related made lots of girls question their sexuality in the 90s and it's not even the oldest example.