Originally Posted by freecia

It probably isn't quite up there and doesn't meet @NZJuniorDoc's criteria for rotenburo but Tsuta Onsen has an annex with private dining rooms for annex guests and in-room onsen https://tsutaonsen.com/annex/ No rotenburo but an interesting ground fed onsen and there's a private bookable one. There are also a few remodeled rooms in the central building but the in-room baths there are not fed by onsen water. I've booked Kakukan remodeled room for an upcoming stay in November.

I'm also looking for a similar Tohoku (& southern Hokkaido) trip and would like some recommendations for around Sendai towards Niigata. Is Saryo Souen the recommendation over Daikon No Hana or further out to Sakurayu Sanshuyu in Yamagata? Any feedback about Kikuya in Niigata?

We are probably going to Hakodate and I noticed Ryotei Kuki on the Western coast a bit of a drive away. Is it worth adding a night after two in Hakodate (main point is going for the ferry to Oma)? It is too bad there isn't a rotenburo with a sea view.

I enjoyed my stay at Miyakowasure. It is definitely a bit out of the way and your opinion on Nyuto is similar to mine with experience to back it up. It gets crowded.