On this episode, Hime goes to the school's pool along with the student council.
So I still think Hime is an actual girl along with his "brother", Kaguya. The main reason on why is because our "male lead" is cautious or gets embarrassed if his chest gets shown. Other than that, it's nice to see why Hime doesn't swim and more fan service. Overall, funny school pool episode.
Conclusion: Funny school pool episode.