Slick and Smooth
Smooth drawings, slick animation, what more can I say? That's was really nice! And honestly I loved the design of the kid; he was essentially the picturesque image of a boy bored in school. Perhaps I'm ignoring the whole monster thing but the design of everything was really nice. The expressions were nice, the sharp broad lines you lined everything with... Also for some reason the bodies seemed more proportionate than your older works. And maybe I also love that you didn't outline any of the background in black.
This style of yours is a keeper; do whatever you'd like with your style but it'd be amazing to see something like this in the future.