Uses natural hot spring water
Facility name/copy identifies it as an onsen inn in Senami Onsen; corroborated by 2025-2026 reviews describing 源泉かけ流し (source-fed, non-recirculated water).
Open-air outdoor bath
Enclosed indoor bathing area
Dry heat sauna room
Private bath available for day-use visitors or hotel guests to reserve
Aggregator (Rakuten Travel) additionally lists reservable hours 15:00-23:00 in 45-minute slots, booked at check-in.
Private onsen bath in guest rooms, for overnight guests only
Shared bathing area for all genders
On-site or nearby parking available
Seiunso is a ryokan on the Senami Onsen coast in Niigata. Its main bathhouse, Komoriyu Sorin-an (籠湯 蒼林庵), holds both an indoor bath and an open-air rotenburo, separate for men and women, all looking out at the Sea of Japan. There's also a private kashikiri bath with its own outdoor tub, and a few guest rooms come with their own open-air bath. Out on an open sundeck, a foot bath called Tenku Kairo (天空回廊) faces the same view. The onsen water is fed straight from the source rather than recirculated, and guests often mention how gentle it feels on the skin and how long the warmth lingers afterward. It's an older seaside inn, plain and comfortable, with rooms that have been refreshed in recent years.
Loading map…
Reserve or check availability on a booking site.
No reviews yet
Be the first to share your experience!
Last updated July 30, 2026