Here is a small but interesting museum that is very interesting, especially if you are traveling with kids. The English audio guides are a must-use.
The Advanced Technology Exhibition Hall@TEPIA displays advanced technologies, as well as progress in the realms of daily life and society, in an easy-to-understand fashion. Centered on fields such as telecommunications, health, medical care, the environment, and energy, the focus of this enjoyable, hands-on exhibition facility is Japan's world-famous advanced technologies and products.
Wow. I had never heard of this museum but it looks amazing... and reflective of Japan's great technology :)