First Reddit post couldn't come for a better occasion haha. I need your help!

I'm traveling to Japan for 7 days in 2nd half of December 2023 (on my way to US west coast). I'm entering and exiting through Tokyo. I'm looking to spend ~4 days in Tokyo, and want to keep the remaining 2-3 days for just one other city / place.

I am looking for suggestions / recommendations on the 2nd city. Here are some things on my mind for the 2nd city.

• I do not want to do another major city like Tokyo (So Osaka seems out). As of now, Kyoto is one of the options (based on the threads I've read and other research)
• While Tokyo is a metro city, with lots of people, I want a low-key city which is less crowded.
• When I travel, I am very curious to explore how other cultures live the habits that are common with me (fitness habits, sports, music, work culture, food habits, school trauma, dating habits etc etc) which are often revealed when I dive deeper into a culture by spending time with locals.
• At the same time, I know Japan has entirely new concepts and ideas that I wish to explore as well.
• I do not want to spend excessive time commuting, even though Japan's transportation system is insane!
• I like to travel slow, have some unplanned time in the day for pure exploration.
• I like to Ski as well, so Yamagata prefecture is one of the options (Ski Onsen sounds dreamy!). Any other options?

I'm not sure how vague or accurate this is haha, but I hope I'm able to convey the essence. Please let me know your thoughts!!