No suprise at all that Charles is indeed Charlotte. Anyone who isn't totally blind could already see that last episode.
For the shower scene - why was he so anxious to see another boy naked? That was a bit strange
However, the following scene doesn't allow gay speculations. When he sees that Charles is a girl, he doesn't scream as a gay would have there. Also, he doesn't quickly turn around and leave again.
No, he obviously can't get enough of oglin naked Charlotte, so not only he is in no hurry to leave again, but he even proceeds to hand over the soap. "Let me hand over the soap - I'll get some more time looking at her body, and when she'll take the soap from me with her hand, I'll get a better look at her breasts.
"
He also quickly agreed when Charlotte asked him to feed her (although, who could've resisted her with that face?)
So that leaves two possibilities:
- Ichika was indeed gay before, but seeing Charlotte naked turned him straight again.
- Ichika simply isn't really interested in the other girls, whi is why he didn't show any reaction. After seeing Charlotte nake, he simply can't resist her.