I 'm having a hard time imagining a strong association between innocence and college students of really any age. xD
I could see the argument made for wanderlust--wanting to explore the world or the unknown--, maybe acute sensation-seeking, or more generally a paucity of life experiences, but not... innocence. (I will, however, redouble my efforts to suspend disbelief, if we do go that route.)

That said, I typically enjoy roleplaying within a college/university setting more than a high school setting.

Any preferences on a location? That will drastically change the nuances of any character I create.
Personally, I favor korea, south africa, and the UK as places of interest, particularly large cities/capitals. What about you?