Where should we stop between Tokyo and Osaka ?

My cousin and I are traveling to Japan and have a 1-night gap on April 2–3 between Tokyo and Osaka.

Our plan:
• Tokyo: March 28 – April 2
• Osaka: April 3 – April 9 (with day trips to Kyoto and Nara)
• Tokyo again: April 9 – April 11

We originally planned Hakone for that night but decided it’s not really our vibe, so now we’re looking for a good alternative between Tokyo and Osaka.

We’re looking for somewhere that:
• is easy by train
• is worth staying overnight (not just a quick stop)
• has good food and is walkable
• feels different from Tokyo/Osaka

We’ve considered Nagoya, but are open to other suggestions that make sense for early April.

Any recommendations would be appreciated.

by KeyFit2318