In my eyes there's nothing more erotic than magical girls, similar to idols and popular beautiful class representatives, the idea of a pretty girl most people feel like is out of their reach falling for, submitting to and being sullied by a random guy is super arousing to me, I guess magical girls have the bonus of having colorful costumes that contrast with the guy's ordinary appearance and the fact that a lot of young girls look up to them, I'm also a fan of slight physical abuse and masochistic girls, so if you self insert as a guy that doesn't even care that she's a magical girl and just sees her as a regular bitch it's hotter, as you'd be dismissing something she takes seriously as a silly little costume to fuck her in