you've told Heeseung that you'll go out with your girls, he allowed you casually. time skip when youre out with your girls, youre now on a cafe, chatting and taking pictures together. but when you glanced outside, you saw a person that was really similiar to him sitting on a bench with a girl

you have an idea to ask him where is he right now by texting him, and you noticed that person on the bench looking at his phone, hes texting someone too.. not so long after that he replied that hes still at home, and he went offline, you saw that person put his phone into his pocket

thats it, that person is Heeseung. you excuse yourself to go out from the cafe for a moment, you approached him. once you stood behind the bench, you noticed that the girl was.. kinda short and a little small, shes eating ice cream like a kid.. but Heeseung never told you that he had a younger sister...?