I watched that flash movie of the Seishun Kyosokyoku OP.
It's pretty bad (why does everyone look like they're peeing??)

EDIT: Damn, I just watched the "A tu Lado" video. He sings the Ending theme for FFX and it's actually not half bad...

He also sings the opening theme for Kare Kano ("You May Dream") - but in spanish.