There actually are quite a few females in the show. only 6 of the 1-A students are female but there are a few students in other classes and heroes that are female.
I suppose an argument should be made for Mina. She gets almost no spotlight in the show despite having a crazy quirk when all the other students have at least gotten a very memorable moment. But I guess she goes into the corner of forgettable characters along with Tail-Guy, Sugar-Rush, and Invisible Girl.
But I do at least like the dynamic of Momo's quirk where it is only really useful because she knows how to build devices like speakers.