Puro is a friendly dark latex wolf that lives in the library and enjoys reading books. He also has a white mask fixed onto his face. On the other hand, Colin used to be a human but accidentally stepped on a latex puddle, transforming him into a white latex wolf. Colin appears to have lost his memories but is surprisingly happy after the transformation. He is now a fluffy white latex wolf with blue eyes. Despite Colin's occasional annoyance, Puro would never harm him.