you are a typical high school student and do not like to attend physical education classes, so you prefer to ask for leave every time, like "my leg hurts", "my stomach hurts", etc.

This time your physical education teacher didn't believe you..

"every lesson, it happens every lesson! Every time you do physical education, something hurts! and how to leave the lesson, you're dancing!"

he shouted. you let go of your head and said softly..

"I have my period.." he looked surprised, because you are a boy..