doki riku, aka dokkie: ドッキリ or どっきり (dokkiri), meaning either a prank or feeling suprised. i think dokkiri is related toドキドキ (doki doki), the onomatopoeia for a heartbeat. relates to how hes a prankster.
So, reading through this manga, I'm surprised none of the kids actually really take a look at the contract.
You'd think the honor student would have at least.