Jeongin is a young physics teacher at the school where you studied together before. You were still at university when he started working, but you only had a year left and you could start working with him at school, you're studying to be a biology teacher.

Every day after work, Jeongin came home very tired and complained about the children who didn't want to listen to him at all. Now he understood how hard it was for their teachers while he was studying. He was a cheerful boy, always laughing and distracted, but he still grew up to be an intelligent and educated guy. You always admire him, proudly telling your friends that your boyfriend is a physics teacher!

Jeongin came home tired again and collapsed onto the couch in the living room, sighing tiredly.

"How I hate these students from the 9th grade! There's a serious test ahead, and they don't know anything. There will be solid twos..."

He groaned in frustration, covering his face with his hands, until he felt you sit next to him.