When I first saw this, I thought it was a vending machine.
I think that is a vending machine also. Coins being slipped and go under the vendor machine is such a common scenario in mangas and stories when vending machines are involved. I can image what a surprise it will be for someone who try to reach the coin blindly.
I think those yus are ko yus lost their adults, by the way. Can't image such a group of adult house yus doing so bad surviving...
One of the many fates of orphan yukkuris, starvation...... As their parents took it easy forever, they have no one to count on to survive and as they have zero knowledge about hunting they hide themselves scared of the outside world awaiting mister death to takes them away from such uneasy reality