Depending on the artwork they look like they're made out of either latex or rubber, neither of which seem very comfortable. Squishy at times, but probably a bit too hard for a good sitting session.

My initial reaction is that they'd probably feel like jelly, would likely leave a sticky residue as well

Looks pretty comfy, just so long as you don't fall in the mouth

Like sitting on a sofa surrounded by cardboard

Initially comfortable and would mould around your body pretty well, but definitely a risk of it falling apart and/or melting

Just as above, but you'd also receive an electric shock

Like sitting on a sofa, surrounded by other sofas

Another nice squishy looking surface, might get startled by pointy ends though

Good level of squishiness, comfort may reduce if the giant LocoRoco divides itself too quickly

Plump and feathery, but would likely be crushed by the weight of a human and I don't quite want to get into the mess you'd be left sitting on

Probably what sitting on a water balloon would feel like, high likelihood of bursting as you fall to the floor with a wet behind

Good level of squishiness but probably too small for a whole person to rest on