Chapter 40 says: “Would seungwon remember today after 5 years when he turns 26 years old?”
So the younger guy is at most 21 right now. And I think the older one is 26 right now, judging by how he imagined a 26 yr old joining an idol group wouldn’t have good reactions with the fans.
BRuh the age gap i mean its not bad BUT HE STILL IN SCHOOL??? NAWWWWW