Public bathhouse · Open
Onto
- Day-use bathing
- Yes
- Fee
- ¥990checked 2026-10-09
- Hours
- 10:00–22:00checked 2026-10-09
Photo information
Save to passport
Official classification
Spring type (therapeutic classes)
Official spring-type name (as recorded)Alkaline simple hot spring (Onto)
- Source temperature
- 39°C
- pH
- 9.62
- Flow rate
- 36 L/min
- Radon
- Unconfirmed
Appearance & feel
Water colour · Feel
Unconfirmed
Colour and feel are listed only where a source states them. They vary by day and by bath.
What makes it special
A metre-deep bath stands directly over the rock from which Yamaguchi's oldest spring has flowed for 600 years.
Facilities in this area
Facilities come from the register (Wikipedia, OpenStreetMap, official sites). Those marked "natural spring unconfirmed" are listed on the basis of their name only.
Ryokan (inn) · Open
Otani Sanso
- Day-use bathing
- Unconfirmed
- Fee
- Unconfirmedno check date
- Hours
- Unconfirmedchecked 2026-10-09
Getting there
Reachable by public transport
From Shin-Yamaguchi Station a direct shuttle (shared taxi) takes about 1 hour, 3,000 yen, four a day. From Hakata or Tenjin in Fukuoka the 'Hagi-Nagato Otozure' express bus takes about 3 hours (two return trips a day). The nearest JR station, Nagato-Yumoto on the Mine Line, has been closed since the June 2023 floods; a replacement bus from Asa takes about 1 hour.
- Getting there
- Shin-Yamaguchi Station · 60
- Getting there
- Four direct shuttles a day from Shin-Yamaguchi (11:15, 13:45, 15:25, 16:55)
- Checked
- 2026-10-09
About the water
The water is a strongly alkaline (pH 9.62) simple spring: low in dissolved minerals and gentle on the skin. It emerges at 37–39 °C, close to body temperature, and Onto lets it flow through unheated, so this is a bath to linger in rather than a hot soak. The bathhouse describes a faint sulfur note. Onto states a natural flow of 131 litres a minute; Wikipedia gives 36.5, so figures vary by source and date.
| Source | Source temperature | pH | Radon | Checked |
|---|---|---|---|---|
| Onto source | 39 | 9.62 | Unconfirmed | no check date |
Three things not to miss
Photo information
Onto bathhouse
Left bank of the Otozure River, centre of the village The village's original bath, rebuilt privately and reopened in March 2020. It sits on top of the spring, so from the tub you watch water rise from the bedrock. Adults 990 yen, 10:00–22:00.
The whole renewal of Nagato Yumoto began with rebuilding this one bathhouse. Its pH 9.62 alkaline water runs through at its natural 37–39 °C, unheated.[2][5]
River terraces and steps on the Otozure
Along the Otozure River through the village Stone steps, decks over the water, stepping stones and a bamboo-grove stairway let you walk right down to the river. Grand prize in the 2021 Japan Society of Civil Engineers design awards.
The heart of the redesign that turned a car-oriented resort into a town for walking, with the river as its main street. Lit at night.[5]
Taineiji temple
Walking distance from the village The Soto Zen temple whose abbot is said to have found the spring in 1427 after a revelation from the deity Sumiyoshi.
The baths were named Onto ('gratitude bath') and Reito ('thanks bath') for this story; here you can trace where the names come from.[4]
The story
A spring found by revelation
According to tradition, in 1427 the abbot of Taineiji temple found the spring after a revelation from the deity Sumiyoshi. The two baths were named Onto and Reito, 'gratitude' and 'thanks', and in the Edo period the lords of the Choshu domain came here for cures. It is regarded as the oldest hot spring in Yamaguchi Prefecture.[4]
Rebuilding a town from one bathhouse
In 2016 Hoshino Resorts decided to open its 'Kai Nagato' inn on the site of a defunct hotel, and the town's renewal began in earnest. The municipal Onto closed in 2017 and was rebuilt by a group of young locals, reopening in March 2020, the same month as Kai Nagato; the sister bath Reito closed at the end of March 2019. Architect Shohei Oka placed the new bath directly over the source so that bathers can watch water rise from the rock.[5][4][2]
A resort with the river as its main street
Along the Otozure River, stone steps, decks, stepping stones and a bamboo-grove stairway create a route that follows the water rather than the road. The public-private scheme won the Japan Society of Civil Engineers design award and a Good Design Award for 2020, and more than 15 new businesses have opened since. Seasonal events such as the autumn ceramics fair and the winter river lights have taken root.[5][4][3]
Going solo
Easy for solo travellersUnconfirmed
Weekend / peak restrictionsUnconfirmed
Where to eat dinnerMore than 15 new shops and eateries have opened since 2020 (Mirai Project)
Private bathYes
checked 2026-10-09
Through the year
Recommended months
JanFebMarAprMayJunJulAugSepOctNovDec
Months open
JanFebMarAprMayJunJulAugSepOctNovDec
"Recommended" and "open" are recorded separately. Check the season for seasonal springs.
Oct · Nov — 'Utsuwa no Aki' ceramics festival (2 Oct–3 Nov in 2026, free), with pottery shown and sold around the village
Jan · Feb · Mar — 'Otozure River Uta-akari' light event (15 Jan–7 Mar in 2027) along the river
Food, culture & experiences
Taineiji temple
The temple of the founding legend; known for autumn leaves[4]
Walking distance from the villageUtsuwa no Aki ceramics festival
Autumn pottery festival, 2 Oct–3 Nov in 2026[3]
In the villageRiverside decks and steps on the Otozure
Walk down to the water's edge[5]
1 minute from OntoEditors' guide
Start at Onto with a long soak in the 37–39 °C water, watching it rise from the rock. Afterwards walk down the stone steps to the river decks and on to Taineiji temple. Visit during the autumn ceramics fair or the winter river lights to see what the redesign was for. The railway is suspended, so plan around the Shin-Yamaguchi shuttle or the express bus from Hakata.
The "editors' guide" above is written by the editors from sources; it is not a visitor's opinion.
Photo gallery
Visitor reviews
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Onsen areas nearby
Unconfirmed & notes
- Tattoo policy, towel sales and last entry at Onto not confirmed
- Flow figures differ between Onto (131 L/min) and Wikipedia (36.5 L/min)
- Solo-stay terms and day bathing at individual inns not confirmed
- The JR Mine Line has been suspended since June 2023 (official notice as of Oct 2026); reopening date not confirmed
Sources
- 長門湯本温泉 公式サイト長門湯本温泉まち株式会社 · 2026-10-09
- 恩湯 公式サイト(料金・泉質・施設)恩湯 · 2026-10-09
- 長門湯本温泉 アクセス長門湯本温泉まち株式会社 · 2026-10-09
- 長門湯本温泉 - Wikipedia(日本語版)Wikipedia · 2026-10-09
- 長門湯本みらいプロジェクト長門湯本温泉観光まちづくり推進会議 · 2026-10-09
Register sources
- 長門湯本温泉 - Wikipedia(日本語版)Wikipedia · CC BY-SA 4.0 · 2026-10-09
- Wikidata Q11654891Wikidata · CC0 · 2026-10-09
Data status
Name & locationPublishedCoordinatesPublishedSpring typePublishedPhotosPublishedFacilitiesPublishedVisiting info (dated)PublishedEditorial articlePublished
Updated 2026-10-09
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