Was the twist that Mizu was a girl actually surprising?

I found about the show when I watched some guy's skit on it, and in that video and the comments, everyone addressed Mizu as a girl, so the whole reveal at the end of episode 1 wasn't really a surprise to me.

But I recently started wondering: Did anyone actually find that surprising? I mean, for me, I have the hindsight of knowing she was a girl all along, but what about y'all who didn't get spoiled? Did her disguise actually work on you or was it obvious?