EDIT to include favorites and a new link.
For those who don't know, yokai are monsters and spirits from Japanese folklore.
So far the only yokai i've seen on Subeta is the kappa, yukisumi items and some various kitsune, but I would love to see more.
Some of my favorites,
Futakuchi-onna: a lady with a hungry mouth hidden under the hair on the back of her head!
Karakasa: a yokai that transformed from and old parasol, usually depicted with one leg, one eye, a long tongue and spindly arms with claw like fingers.
Tsukumogami: yokai, like the Karakasa, which transformed from old worn household objects like zori sandals and kettles.
Nurikabe: a large invisible wall that often appears in dark streets and alleys to hinder people progressing forward, sometimes depicted as a large fleshy wall type creature with a pug face.
Rokurokubi: Appears as an average woman by day but by night while the body rests the neck becomes impossibly long and snake like so that the head can roam freely!
And of course there are a ton more :)
I thought i'd add a link to a fabulous collection of Yokai information and images! It's more or less a yokai encyclopedia.
YEs! Self-servingly supporting this because I happen to have a youkai pet =d
Imagine walking down the street, just minding your own business, and seeing a Shirime speeding in your direction. There's some crazy stuff in that list. I would love a Shirime minion but I'm not sure how the staff could put that on site. They took the X off the Oxycafos.
Some of my favorites from that list are the Uwan, Tenome, Heikegani, Jinmenju, and the Nue. I also love kappa and wouldn't mind more. I really liked the zashiki-warashi in Mononoke. They've got that so-ugly-it's-kind-of-cute thing going on.
Bonus points if the artists can keep some of that ancient Japaneses art style intact.
I'm going to do a whole lot of NOT imagining that one, haha. While i'm not a fan of the Shirime, Subeta does have the so if they wanted to they could probably make it work and traumatize humanity.
I love those others that you've listed though along with the Amabie (mermaid-ish), any kind of Tsukumogami, crow tengu, Kechibi (fireballs with human faces), Nurikabe (the wall) and Rokurokubi (long necked woman).
The Shirime is fun in a immature giggling sort of way, though terrifying to see in real life I'm sure. I'd completely forgotten about the Booty Picker. I guess that's okay maybe because there's no obvious booty hole or that it just looks like a butt.
Tsukumogami are a really neat concept. If this suggestion does get picked up I'd like it if at least some of the released items weren't people/animal-ish.
Also Nurikabe are adorable.

These sound like they might make an awesome set of Quest Shop minions in Quentin's shop!
Me want and me need.