This is Higashiharai Park (東原井公園). It's a teeny weeny park with two benches, a sandbox, and two animals on springs.
When I passed by there was no one there. But, from the looks of the handles, it seems like a lot of kids have ridden on both the panda and koala.
I remember I really liked this when I was little, too. My sister and I used to bounce around like crazy. I'm surprised we didn't pull the thing out of the ground!
I imagine many kids made the same kind of memories here, too.