I'm a Japanese developer living in Fukuoka. Someone on Reddit planning their first trip to Japan (16 days, Tokyo → Hakone → Osaka → Kyoto → Japanese Alps → Tokyo, interested in food, anime, and onsen) asked for advice on their itinerary. This is what I told them.
Overall, I don't think it's too packed. It should be manageable as long as there are no major transportation issues, but you should leave some flexibility so that you can skip one thing if you get tired.
If I were you, I would make some time to eat in neighborhoods where locals spend time, rather than only visiting tourist spots. If you drink, Hoppy Street in Asakusa and the area around Ameyoko in Ueno would be easy to fit in, since Asakusa and Ameyoko are on most first-timer itineraries anyway.
There are plenty of izakayas and standing bars, and those areas are lively at night, with lots of locals and younger people around. If you're interested in a more local atmosphere, Kamata or Oimachi could also be good options.
If Asakusa and Ueno are already in your plans, you don't need to force Kamata or Oimachi into your itinerary — just having a relaxed meal around those areas would be more than enough to enjoy the local atmosphere.
I build FindEats, an app that helps travelers find restaurants in Japan by reading what Google Maps reviews actually say, instead of relying on star ratings.