What factory tours are there in Tokyo and which are the best?

I am a big fan of technology and have heard that in Tokyo that you can go on free factory tours of big technology companies. I would like to know which companies offer these free tours, which are free, which are the best, which are in English. Really, any info on Tokyo Factory Tours would be great – I am going later this month. Thanks

Unfortunately, there are no factory tours in Tokyo because the companies in Tokyo operate offices instead of factories.
Well, the closest thing to a factory tour that I can think of it the ANA maintenance place.

However, if you could travel out of the Tokyo area, there are interesting tours in Sendai, Aichi, and Hiroshima.
Sendai has the Nikon factory tour.
Aichi has the Toyota factory tour in which you can see Toyota cars being assembled.
Similarly, Mazda offers a factory tour in Hiroshima.

…WAIT!

If you’re a big fan of tech, I can recommend a few places to go to in Tokyo.
1) You can visit the Miraikan, which is a very interesting museum that displays innovative and experimental technologies such as ASIMO and model Maglevs.
2) There are many showrooms in Tokyo which feature products and concepts from famous manufactures such as Canon and Sony.
3) You gotta visit Akihabara!