My sister and I recently did a drawing of TOKIO as little kids (relative ages aren't accurate, because by the time Nagase could roll over, Leader would already be around 9 or 10! We still made Nagase the baby, though) and I think it came out pretty cute.
Yes, I do think little Leader wore sweatshirts that said "Leader" on them. :D I think we made it pretty obvious who's who, in any case.