Semi Onsen, Mogami, Yamagata
Semino-yu Public Bath
Semino-yu is a strong-value way to try an indoor source-flowing bath and a separate outdoor spring in one visit. Bring coins and toiletries, and check that the bath is open before travelling.
Facility photos
Check before bathing
- Opening hours
- Admission is ¥500. Monday through Saturday: 06:00–09:00 and 12:00–23:00, with cleaning from 09:00–12:00. Sunday: 06:00–23:00. Bring five ¥100 coins for the coin-operated entrance; there is no change machine. The bath reopened on May 19, 2026, after a temporary closure, but check for maintenance notices before travelling.
- Access
- In the Semi Onsen area of Mogami. Current local pages checked do not establish a convenient day-use shuttle; confirm your route before setting out.
- Tattoo policy
- The current town and tourism pages checked do not confirm a tattoo policy. Ask the bath before visiting.
Spring & water temperature
- Spring-source temperature
- Not published for either current source
- Bathing temperature
- The indoor bath is listed at about 43°C and 45°C in its two temperature areas; the outdoor bath temperature is not published
- Spring source
- The indoor and outdoor baths use different sources; current town information does not publish their individual source names
- Spring classification
- Sodium-calcium chloride and sulfate spring, based on Yamagata Prefecture's classification for Semi Onsen; a current analysis for each Semino-yu bath was not confirmed
- pH
- Not published for the current individual baths
- Flow rate
- Not published for the individual bath; district figures are not substituted
- Water handling
- Mogami Town describes the indoor Nagomi-no-Yu as free-flowing. Local tourism information says little water is added to the indoor bath, keeping it close to the source. The outdoor Yagen-no-Yu uses a different source, but current pages do not itemize its treatment conditions.
Bathing indications
Yamagata Prefecture lists general bathing indications for Semi Onsen. These are not treatment guarantees.
Admission is ¥500. There are no shampoo, body wash or hair dryers. The facility reopened May 19, 2026 after a March closure; the town has discussed repeated maintenance closures, so check for a current notice before a long trip. Tattoo rules are unconfirmed.
How to read a bath profile
Spring-source temperature and actual bathing temperature are kept separate. Each score is shown independently for comparison rather than collapsed into one overall score.
