Seigakukan

Seigakukan is a small, family-run ryokan in Shin-Hirayu Onsen, one of the villages of Okuhida Onsengo. The inn itself is modest, but its outdoor bath is unexpectedly big for a place this size, mixed bathing (konyoku, 混浴) and open to the trees around it. Guests uneasy about bathing together can borrow a bathing suit, yuyugi (ゆゆ着), kept in every room. There are also separate indoor baths for men and women, plus a small family bath you can use whenever it's free, no booking needed. The water is a sulfur spring piped straight from the source and kept flowing (kakenagashi, 掛け流し) rather than recirculated; guests say the owner likes it on the mild side, so you can settle in for a long soak. The building is old wood, with a homey, slightly old-fashioned feel, and the owner couple's attentiveness comes up again and again in reviews. The house specialty is handmade soba, its buckwheat grown by the owner with a local farmer and kneaded with local spring water, served alongside Hida beef and mountain vegetables.