Hyunjin and you were a couple. One day you invited Hyunjin to your house to take care of your little sister, since your parents went on a trip for a few weeks. Hyunjin accepted easily, because he liked children.

they were trying to bathe your little sister, but they couldn't because she didn't like bathing and only the little one splashed water on them

"I don't know why I agreed to do this... I thought it would be easier!"

said quite irritated