Right Onsen

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How we know this

Every fact on this site is distilled from Japanese-language sources and carries the number of visitors who stated it and the years they said it. Where the evidence is thin, the page says so. This page explains exactly how that works, in numbers.

Where the facts come from

Most Japanese baths have no English page anywhere. What they do have is Japanese visitors writing about them: the water, the price, the hours, the lockers, whether tattoos were a problem. We read those reviews in Japanese and distil them into English facts with a count and a date range.

We never republish review text. A quote belongs to the person who wrote it. What we publish is the counted fact — "stated by 6 visitors · Nov 2025 – Aug 2026" — which is also more useful than one stranger's sentence, because it tells you how many people found the same thing and how recently.

Alongside the reviews we use the facility's public listing (opening hours, closing days, phone, address, the facility's own yes/no on things like an outdoor bath), Japan's Ministry of the Environment statistics, and OpenStreetMap for the nearest station.

What has to be true before we print something

A fact reaches a page only if all of this holds:

In Gunma that gate turned 1,425 extracted claims into 1,156 published facts. 834 attribute slots stayed empty because the evidence was too thin, contradictory, or absent. That is the point of the gate, not a failure of it.

Tattoos: why we so often say "not known"

This is the one fact where being wrong hurts you at the door — undressed, at the counter, being turned away. So it never rests on a single visitor. Of 41 tattoo observations we extracted in Gunma, only 8 were stated by enough people to publish.

Where we say "Not known · call ahead", that is not laziness: it means we read every recent review and nobody mentioned it. The line tells you how many we read. And where a visitor did report a policy, we write what they observed — never "tattoos are allowed here" as though the facility told us.

What "no visitor reviews yet" means

Some baths are too small or too new to have Japanese reviews with usable detail. Those pages stay live in a reduced form, built from the public listing and government data, and say so plainly. In Gunma: 158 pages with verified visitor facts and 0 listing-only pages.

Coverage and sources

Gunma: 158 bath facilities. Japan's Ministry of the Environment counts about 250 onsen public baths in the prefecture, so we are close to complete but not there yet — and small unlisted neighbourhood baths are the ones most likely missing.

How often this is updated

Opening hours, closing days and whether a bath has closed permanently are refreshed monthly. The review-derived facts are re-read once a year, before the autumn and winter bathing season, because prices and rules change with the season rather than the month — and every claim carries its year range so you can see how fresh it is.

Something wrong? Tell us

If a price has changed, a bath has closed, or a tattoo policy is not what a page says, we want to know — you are standing in front of it and we are not. Use the form at the bottom of that bath's page, or the site-wide form below. Corrections from people who were actually there beat anything we can distil.

Contribute

Spotted something out of date?

Tell us which bath and what is different. It is corrected in the next run. Everything below is optional except the last box.

Contributions are reviewed before anything changes on Right Onsen. A single report tells us where to look; it does not become a fact on its own. We never publish your email address.

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