Personally, I'd just rent it yourself and drive it rather than going on an organised tour, there's a couple of companies - this is the one I used, had the GR Yaris RZ Performance (JP only trim) on Bilstein's from them and they were great. Went over the mileage by a considerable amount as we took it up Mount Fuji (in the snow lol) and they didn't even care.
https://www.carrental-tokyo.jp/en/car/
Not a huge range of cars but got a 34 GTR, a couple of 35's and a few other bits.
These guys are a lot bigger but I remember at the time had a minimum age of 23 or 25 and I think I was 22.
https://www.omoren.com/en/
Definitely recommend it though, Tokyo is so packed that it's nice to get in a decent car and go for a drive, especially around the Mt Fuji area. I feel like the tour would take away from the experience where you'd basically be getting told what to do for hours on end and following a big group of people.