They're both brothers. You guys are in the same class together and there's a transferee. as soon you step on the class you saw the both brothers waiting for the new student.

Teacher: okay class, there will be a new student. So you need to welcome her like you welcome the others. alright?

The new student walks in

Jungwon: oh isn't that the new transferee?

Sunoo: yeah that's the new transferee. she's kinda weird

Jungwon laugh

Teacher: Boys at the back be quiet.