Official art of Nicolas (Source)
From the Greek name Νικολαος (Nikolaos) which meant "victory of the people".
Nicolas is the protagonist of Dream Syndrome.
Nicolas is a young mouse boy with short tan-ish hair that covers his eyes. He wears a black beanie on his head and seems to wear a large black and purple sweater that covers most of his body.
Not much is known about Nicolas's personality.
Unlike other Yume Nikki protagonists, Nicolas doesn't appear to be shutting himself in. He seems to be only aiming for "some proper sleep."
This could be because he's mostly stable in terms of his life. He may possibly suffer from insomnia given his wishes.