I did a solo trip for 16 days in Nov, going between tokyo-kanazawa-hakata--hiroshima-kansai(Osaka/Kyoto/Nara)-matsumoto-nikko-tokyo. Maimized use of 2week JR, wanted to see sumo in hakata

Stayed in capsule hotel (wanted to try it out) and business hotels (lower budget)

The budget on site is accurate. Was aiming for sub3000yen capsule and sub9000 business hotels. Harder to find it in Kyoto/tokyo (had to go to 12000)

Food wise, there's a huge spectrum and variety of good food. I would recommend to lose weight before trip and increase budget for that, eat everything