Tsukioka Onsen Mashu
月岡温泉 摩周つきおかおんせん ましゅう
Day Use
NoBathing & Water
Uses natural hot spring water
Open-air outdoor bath
Dry heat sauna room
A reviewer notes the two saunas run at a mild temperature.
Cold water plunge bath, typically used after sauna
A reviewer describes the cold-plunge water as very lukewarm, more like a still pool.
Capabilities
Private bath available for day-use visitors or hotel guests to reserve
Reservation-only private bath using Sado akadama stone, 45 minutes for 2,200 yen, bookable after making a room reservation.
Private onsen bath in guest rooms, for overnight guests only
Top-grade rooms have a half-open-air bath and other rooms a view bath, but both use heated tap water, not the source spring.
Shared bathing area for all genders
Two large baths, each split by time-of-day between men and women (they swap on a fixed schedule), not mixed bathing.
Policies & Services
Shower, wash stations, soap and shampoo provided
Relaxation space for after bathing
On-site or nearby parking available
Views
MountainsAbout
Mashu is a 38-room ryokan in Tsukioka Onsen where the open-air baths run undiluted, emerald-green sulfur water straight from the source. The indoor baths, by contrast, use heated tap water rather than the spring. There are four outdoor baths split across two bathing halls that swap between men and women depending on the time of day, plus a small reservation-only private bath lined with Sado akadama stone. Renovated in 2018, the inn leans quiet and couples-oriented rather than group-focused, with a garden-facing lounge for unwinding after a soak. It takes overnight guests only; day-use bathing isn't offered.
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Last updated August 5, 2026