A science museum and planetarium. The exhibits are very hands on and aimed at schoolchildren. Unfortunately, unlike a lot of Japanese museums there are very few english explanations or captions. I found the old Zeiss planetarium projector quite interesting as well as an artificial vortex spanning a number of floors. Outside there is a Japanese space rocket, which you can examine even without entering the museum. Not an exhibit but the hydraulic pistons for earthquake damping are interesting too