ksandness introduced the concept of goodwill guides to you back in May, but you obviously didn't quite get it at the time:

Problem with the volunteer guides is that (as AlwaysAisle has also commented on) there's no guarantee that they'll know very much about their own city. Often, those who are most qualified to have a conversation with you are fluent precisely because their real interests are outside of Japan.
I was approached by a volunteer guide in Meiji Mura once, she was very nice but I had to ditch her as quickly as I could because she knew less about the architecture and the park than I did - and I was pretty clueless.

My suggestion to make the most of a guide is to ask you to accompany you somewhere such as the Edo Tokyo Museum in Ryogoku and get that visit to coincide with a guided tour. It's nearly impossible to get a tour in English so your guide can help you understand what is actually going on. That way, you make the most of the guide's expertise - English and having the chance to practice - and you get to benefit from someone imparting real knowledge and insite on Tokyo History.
If you hit it off with your guide that's great. Not everybody will.