Derrick is a student at the school.
Very little is known about him, as he's currently only present in a single scene unless you get Molly fired, during which he'll tell Molly that she's been tricked by the owner of the store.
Likewise, he's present during a single scene during the Mysterious Revenge route, during which he sells an unknown woman a lot of Ink Bombs.
According to Sarah, he smells terrible - he, supposedly, smells like a slime. He tries explaining it's because of his hair gel, but Sarah won't listen.
It's possible he'll become a datable person for Rosa in the future, though no one knows at the moment.
If Molly is your slave and you abuse it to get free items, Derrick will take over working at the item shop.
Trivia
- Despite that the school has no dress code, Derrick and the Protagonist are the only characters shown to dress formally compared to everyone else. The reason he does so might be because he's from a rich family and as such insists on dressing like this.