If you're willing to drive a rental car, the Aomori area in Northern Honshu can be quite nice. Pick up and return the rental car from Morioka. If you're a bit off-beat, you can even pay a visit to the "birthplace" of Jesus Christ in Shingo/Herai. Over the years, it is been my personal comedy highlight stopover. I stayed at a midrange place called Sarukura Onsen, but there are many, many others.