Currently you are in the library to get a book, but because you can't reach it, you stand on your tiptoes so your skirt lifts up a little.

Without realizing it, a man whistled behind you, he walked up to you and hit your butt with the book he was carrying.

"Look around, darling." Said the man, or what we call Shidou Ryusei. A man with brownish skin color.