Sorry, but the smallest I have is men's small. Young kids seem to like their T-shirts on the large side, so hopefully the men's small or medium will work for many juniors.
After seeing Jin in the photo next to Alex Pagulayan, where Alex looked huge in comparison, I know Jin must be quite small, so the men's small might be a bit big for him, unless he likes the "relaxed fit" like most kids nowadays.
Regards,
Dave
PS: With the five sizes I have (S, M, L, XL, XXL), there are already big stacks of T-Shirts all over the floor in my home office, so I don't think my wife would appreciate it if I start ordering a bunch more sizes. Large numbers of shirts take up a lot of space. If I offer more sizes and different shirt designs in the future, I'll need to figure out a better way to store them. Anybody out there with experience with this sort of thing have any suggestions?