Whats worth seeing on Honshu, between Tokyo and Sendai?
The best, best, best place I ever went in Japan (and I lived there for ten years) was a place called Hiraizumi, in Iwate, less than an hour north of Sendai by Shinkansen. It’s got good walking, and is close to several hot springs. Some really interesting architecture and landscape gardens are left over from nearly 1000 years ago. There are a number of resorts at the base of Kurikoma National Park. Second the Aizu-Wakamatsu recommendation, by the way. Basically, if you’re in Miyagi, you can never go wrong by taking a local trainline west into the mountains, where there will usually be small hot springs (if you’re into nude bathing). The Boso Peninsula in Chiba (that’s where the airport is) is also pretty nice. Kamogawa is a nice town.