Sorry, my long-timer colleagues here are not very helpful .
I would suggest :
Disneyland
Sanrio Pro land
Moomin land
The War Museum in Yasukuni shrine where you will learn that basically all Japanese soldiers and their generals were the good guys
There is also something to be said for the vicinity of Fukushima dai-ichi plant. Very quiet , perfect for glamping , fishing etc. I love the big outdoors