On pandora hearts, when Oz returns to his world, and they say ten years went by… is he still fifteen? Because he still looks like he is.
He is still fifteen, but if you got kinda farther in the anime.
They said that Oz came from the past. So when he escaped the Abyss, he returned into a different time period. Thus he is still 15.
Pandora Hearts – Alice Kisses Oz’s Eyes
|Pandora Hearts Oz Vessalius Cosplay Costume