Truly a pleasure
The scenario presented here was divine, wonderfully creative. I especially appreciate that the majority was portrayed in black and white, with the exception of the various painted expressions. The music fit well and held pace with the animation.
I also took notice of the teacher's movements as he roughly grabbed children and gave them their marks. The dripping and splotching held true to the mood, and as it was revealed that the teacher wore the most masks and was likely the worst off, it felt like the last pieces of the puzzle were clicking neatly into place.
I wondered if there could be a conclusion for this fascinating setting, but I think the answer to that is for the society to come full circle, ending with the boy donning his own forced smile. It's pessimistic or defeatist sentiment, but I think that's the story being told.