「こんなこともあろうかと私、制服の下にスクール水着を着込んでおきました」

つぐみちゃんならやりそうだ
おのれ小癪な…いやこれはこれで…

"I wore my swimsuit underneath my uniform just in case something like this would happen"

This is just the sort of thing Tsugumi would do...
That cheeky little... No, actually this is...