[@Ammokkx] She wore her swimsuit underneath her clothes so she doesn't have to get changed out of her clothes. Yeah, that isn't something you would normally do in front of public eyes, but I've seen it happen in anime. It's normal at the beach for someone to just strip out of the top layer of clothes to reveal their bathing suit.

But she would have used the changing booth if her swimsuit wasn't already underneath her clothes.

Also note, that Tsukiko has never been to a public school and she has little experience when it comes to public areas, but she has dignity. She wouldn't just change into her swimming suit if she didn't have it on in front of everyone else.

But for what it is worth, if you don't approve of that action despite she was wearing it underneath her clothes I will use the changing booth and have her not wearing it yet next time.

By the way, are the changing rooms gender specific?

[quote=@1Charak2]
[@Eklispe]

This Man asks a good question

Who the hell brings a swimsuit to the desert? 

[/quote]

Anyone that doesn't want to be cooked alive. It's quite normal for someone to bring a swimsuit to a desert. It's an easy place for them to get a tan too.