Entrance into the park is 400-yen for adults. There is more information here.
Looking down from the top of the rollerslide. There is a complex series of nets to climb on to the left.
We were the only ones at the playground, so we had plenty of attention/help. One of the workers made sure we saw these colorful inflatable balls. There was just enough wind to make these a lot of fun. There were several busses of schools there as we were leaving.
That big white thing is not very bouncy, nothing like the fluffy domes. This was more like running across a water bed.
If the playground is your destination, park at the West Entrance, it's closer. Parking costs 300-yen for a normal size car. There was no lot attendant when we arrived, so the park workers had me pay for parking at the ticket window.
English maps are available, but the one I received was a bit out of date, but you won't have any trouble finding things.