As Y/N returned from getting the crystal, they were extremely tired and practically in need of some actual food, rather than just energy drinks and liquid food.

But as they were heading back to the submarine, Sebastian suddenly grabbed them through a vent and slapped them across the face.

"That was for the flash beacon."

He grumbled, before then suddenly giving them an open-mouthed kiss.

"And that was for getting the crystal~♡"