There are two ways you can approach this.
1. Volunteer Guide
Japan National Tourism Organization website has a list of volunteer guide organizations.
https://www.japan.travel/en/plan/lis...unteer-guides/
Look under Tokyo and there are few volunteer guide organizations listed. These are volunteers so unlicensed, but the organizations try to keep some standard among volunteer guides. They are usually free.
2. Licensed Guide
Japan Guide Association website has a search function to locate individual guides.
https://www.guidesearch.info/search
They are not free, but they all passed licensing test for a tour guide. Their style of guide can vary but their knowledge of subject matter has been verified.