COCOFURO Masunoyu: A Black Spring Bath Beside Kugahara Station
One minute from Kugahara Station, Masunoyu has a free-flowing black spring, carbonated bath and sauna. Adult bathing is ¥600; sauna costs ¥100 extra.
Masunoyu is easy to drop into: Kugahara Station is about a minute away, the doors open at 6 a.m., and an adult bath costs the standard ¥600. The unusual part is what sits inside this small bathhouse: naturally dark spring water, a cold tub filled with untreated source water, and a sauna for just ¥100 extra.
The spring matters more than the COCOFURO label
Masunoyu is not a music-event sauna like COCOFURO Takano-yu or Kagayokujo. Its main draw is Ota’s black spring. The operator describes the black-water bath as a free-flowing natural hot spring and also offers a chilled, source-water tub shaped like a small ceramic bath. The latter is a single-person-sized soak rather than a wide communal plunge, so expect to take turns if the room is busy.
There is also a high-concentration carbonated bath for a gentler soak. You can make a complete visit without using the sauna: start in the carbonated bath, try the warmed black spring and finish with a brief cool-down if it feels comfortable. The cold tub does not have a permanent temperature published on the current facility page, so figures from an individual visit should not be treated as a fixed setting.
The facility has a sauna, but it is no longer free: current admission information lists a ¥100 supplement. The page still carries older “free sauna” wording in its title, so use the current price table when budgeting. The sauna was refurbished in spring 2026; the operator describes the facility as a sauna and bath complex, but does not publish a permanent temperature or a fixed auto-rolyu interval.
Prices and the early-morning opening
| Item | Price |
|---|---|
| Adult bath, age 12+ | ¥600 |
| Elementary-school child | ¥200 |
| Preschool child | ¥100 |
| Sauna | +¥100 |
| Bath and sauna | ¥700 total |
| Bath towel rental | ¥160 |
| Towel set | ¥280 |
Masunoyu is open 6 a.m.–midnight, with last entry at 11:30 p.m. It closes on the second Thursday of March, June, September and December. Early morning works well for a quick soak before sightseeing or a day on the Ikegami Line; the station-side location also makes it a straightforward stop on the way back to a hotel.
Guests with tattoos should check directly before visiting, since the current facility information does not give a clear tattoo rule. Seven-year-olds and older should not use the opposite-gender bath. This is a busy neighbourhood bathhouse rather than a large resort, so there is no outdoor garden or broad lounge floor to spread out in after bathing.
For the best fit, come if you want the black spring and a low-cost sauna, or if you need a proper bath early in the day. If your priority is a wide cold pool, a large relaxation area or long sauna rounds, a bigger facility will suit you better. For two very different COCOFURO experiences, see the music-sauna comparison.
Sources
- [COCOFURO Masunoyu: current prices, hours, facilities and access](https://cocofuro.com/masunoyu/) - [Rakuya Onsen: Masunoyu facility profile](https://rakuya-onsen.com/experience/masunoyu/) - [Sauna Ikitai: dated Masunoyu visit records](https://sauna-ikitai.com/saunas/2063/posts) - [Ota City: public baths in the district](https://www.city.ota.tokyo.jp/sangyo/sento/about_sento.files/otasentou_yoko.pdf) - [Tokyo Sento Association: adult fare effective 1 August 2026](https://www.1010.or.jp/guide/%E5%85%A5%E6%B5%B4%E6%96%99%E9%87%91%E3%81%AE%E3%81%8A%E7%9F%A5%E3%82%89%E3%81%9B/) - [Consumer Affairs Agency: sauna safety guidance](https://www.caa.go.jp/notice/entry/038208/) Checked: 2026-09-27Tags: COCOFURO Masunoyu, Kugahara onsen, Ota City, Tokyo black spring, Tokyo sauna
