JP-04 · JP-05 · JP-06 · sulfur deep cuts
Ten days through Tohoku's onsen towns. Sulfur, sodium, iron — water chemistry matters more than the ryokan price.
Tsurunoyu first (book 3 months out). The other 6 ryokan rotate through the same hot-spring source — Tsurunoyu is the original.
Mixed-gender, no separation. Don't go expecting an Instagram angle. 42°C, sulfur-heavy.
Hakkaisan + Kubota. Both run tours in English on advance booking. Pair with Echigo-Yuzawa onsen.
Hirosaki Park hits peak around April 22-28. Quieter than Kansai. Bring layers.
Tsurunoyu OK. Sukayu OK. Most Yamagata ryokan still strict. Call before booking.