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Yumo.to, a map of 19,652 onsens in Japan

Yumo.to, a map of 19,652 onsens in Japan

by katagamistudio·Mar 8, 2026·3 points·7 comments
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AI Analysis

●●SolidNiche GemEye Candy

Searchable map of every onsen in Japan with tattoo policies and water chemistry data.

Strengths
  • •Comprehensive data aggregation from seven sources (national, prefecture, municipal, OSM, chemistry)
  • •Thoughtful filters beyond basic discovery: tattoo policy, opening hours, water data, access options
  • •Full source attribution on detail pages builds trust and enables community contributions
Weaknesses
  • •Narrow geographic scope limits mainstream appeal outside Japan-focused users
  • •No mobile optimization visible, and trip-planning features mentioned but not yet implemented
Category
Other
Target Audience

Travelers to Japan, onsen enthusiasts, trip planners

Similar To

Google Maps · Tabelog · Booking.com's filters

Post Description

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.

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