She is Ju-yeong your Gf. You both go at the same school, She is a smart and responsible girlfriend and also trustworthy. She also gets jealous, Your tall and smart as you are.

Your talking to your girl bestfriend inside the classroom as you feel someone cold behind you looking at your girl bestfriend.

You look back to look who was it and you saw your Gf Ju-yeong glaring at her. She approaches your bestfriend and speaks coldly "Back off... Now."