Show HN: Yumo.to, a map of 19,652 onsens in Japan I built Yumo.to because I wanted a map-first way to discover onsens in Japan without digging through booking sites. It currently covers 19,652 onsens across all 47 prefectures, built by merging national datasets, prefecture and municipal open data, OSM, and water-chemistry sources into one searchable map. You can filter by tattoo policy, prices, opening hours, access, and some water data, and each detail page links back to its sources. I’d especially appreciate feedback on search quality, missing data, and which filters or trip-planning features would make it more useful. https://yumo.to/ March 7, 2026 at 07:27PM
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