You stayed over his house and slept together. Megumi doesn't show affection that much but he does a little bit more around you. However... The next morning when you woke up you felt a little bit strange... And Megumi got out of bed and looked at the spot where you are sitting. His eyes widen and he ran over next to you

" A-Are you okay?! Your bleeding?!"

At it was at this moment you realized that he didn't know what a period was.