Higashi-Naruko Onsen Isazen Ryokan

Isazen Ryokan is a traditional toji (therapeutic bathing) inn in the Higashi-Naruko district of Naruko Onsenkyo, a hot spring region in Osaki City, Miyagi Prefecture, whose waters have been used for more than a thousand years. Founded in 1941, the inn sits within a flat village settlement just a three-to-five-minute walk from Naruko-Gotenyu Station on the JR Rikuu East Line. Higashi-Naruko was the site of the Date clan's goten-yu, a bathhouse reserved for the feudal lord during the Edo period, and it remains the quietest, least commercialised corner of Naruko, devoted to self-catering hot spring therapy. The interior is famously decorated head to toe in Hanshin Tigers baseball memorabilia, with tiger-striped stools and buckets in the bathrooms, making it something of a pilgrimage site for fans.

The defining feature is the use of three to four separate spring sources. The inn's own Isazen No. 1 and No. 2 blended source emerges at 42.9C with a pH of around 7.0, a sodium bicarbonate spring rich in radium and known locally as the tansansen or carbonated bath. Isazen No. 3, at 45.1C and pH 7.2, is blended with the Higashi-Naruko communal source to produce the tekkosen or iron bath, which takes on an oolong-tea brown colour. The large bath and open-air bath draw on the Arai No. 2 and No. 5 blended source at 66.4C and pH 7.4, a sodium bicarbonate-chloride-sulphate spring carrying the petroleum-like abura-shu aroma characteristic of Higashi-Naruko. All baths are supplied as free-flowing spring water.

The bathing facilities comprise the mixed-gender indoor bath Isazen no Yu, which holds separate carbonated and iron tubs, the men's large bath Daigoji no Yu, the women's bath Non-chan no Yu with an attached open-air tub, and a private indoor bath, allowing guests to tour three distinct waters within a single building. Towels and bathing garments are not permitted in the mixed bath. Day-trip bathing costs 500 yen for adults and 300 yen for children, from 10:00 to 18:00 with no closing days, though some sources list hours until 20:00, so calling ahead is advised. Free parking is available for 50 cars. Room-only and self-catering toji stays are offered, including 23-hour stay plans and extended multi-night visits.