Tadashi Hiramatsu was the Storyboard, Director, and Animation Director for this half episode alongside 1 of 4 KA artists. Safe to say that majority of the posts uploaded are animated or touched by him in some way. Out of the 3 artists who worked on this half episode none of them have booru uploads, so while that isn't concrete evidence as there are hundreds of unknown stars in the industry, I think it's more probable that the large bulk of what's uploaded is just Hiramatsu in one way or another. I'll keep Artist Unknown for some as formalities and to lessen the chance of accidental mistakes as always, but all the information presented here point to Hiramatz carrying the hell out of this section himself.

(It's 3:30 AM excuse me if this reads like a mess....)