Tokyo · Tokyo City
Kaiseiyu Onsen Bathhouse (Kamata)
天然温泉 改正湯（蒲田）
Kamata, 15 minutes by train from Haneda Airport, has Tokyo's densest cluster of 'kuroyu' black-water springs. Kaiseiyu, founded in 1929, is the classic: a coffee-dark natural bicarbonate bath, a high-concentration carbonated pool and a cold plunge, with a goldfish aquarium set into the bath wall. ¥600; a toiletries-and-towel set is sold at the desk. Ideal before a flight or after a late arrival. Tattoos are fine, as in most sento.
- Price (adult)
- ¥600
- Hours
- 15:00–23:30
- Closed
- Fri
- Access
- 8 min walk from Kamata Station west exit (JR / Tokyu)
- Water type
- Bicarbonate spring
- Tattoos
- Allowed
- Admission
- Adults ¥600 (Tokyo’s uniform sento rate, revised Aug 2026) / elementary ¥200 / preschool ¥100. No shampoo or soap provided — “empty-handed set” (shampoo, conditioner, soap, towel) sold. ¥100 refundable lockers
- Baths
- Four tubs — kuroyu (black water) onsen, kuroyu cold plunge, silk bath, massage bath and high-concentration carbonated bath. No sauna. Instead of a painted Mt Fuji, the bath wall holds a large aquarium of goldfish and koi — the house signature. Push-button showers
- Water
- Kamata’s signature “kuroyu” — a sodium bicarbonate-chloride cold mineral spring coloured tea-black by humic acid from ancient plant matter. Even the cold plunge is black water. Alkaline and skin-smoothing
- Parking
- Small free car park. 7–8 min on foot from JR Kamata west exit
- Phone
- 03-3731-7078
- Official site
- kaiseiyu.com ↗
- Open in Google Maps
- Google Maps ↗
Essentials
Stay in this onsen town
Compare and book stays in Tokyo City. Day bathing itself needs no booking.
Opens partner booking site (affiliate)
Why go
- 15 min from Haneda, black-water bath
- Goldfish tank in the bath wall
- ¥600, tattoo-friendly
Kamata’s black-water bathhouse with swimming goldfish — a genuine onsen for ¥600
Ota ward, home to Kamata, has more sento than any other of Tokyo’s 23 wards and is known as the “Kamata onsen district” for the black natural spring water, kuroyu, that wells up all over it. Kaiseiyu is a flagship example: a neighbourhood bathhouse dating from the 1950s, modernised in a refit yet still charging Tokyo’s uniform sento rate of ¥600 — a real onsen from deep underground for the price of a bath. The tubs are a solid line-up of kuroyu onsen, kuroyu cold plunge, silk bath, massage bath and high-concentration carbonated bath, and in place of a painted Mt Fuji a large aquarium of goldfish and koi decorates the bath wall — a much-photographed feature. There is no sauna, but alternating the black cold plunge with the carbonated bath is refreshing enough. Bathhouses here tend to be tattoo-tolerant (Kaiseiyu allows them), and Haneda Airport is 15 minutes away on the Keikyu line — a fine last soak before flying home.
Tips & cautions
- Opens 15:00, closed Fridays; busy with locals in the late afternoon and evening.
- No shampoo or soap provided — buy the set at the counter or bring your own.
- Lockers and shoe boxes need a ¥100 coin (refunded).
- Sento manners: wash before entering the tubs, keep towels out of the water.
- No sauna — for sauna try nearby Yu-City Kamata (extra charge).
- Kuroyu can stain towels and swimwear (mind white towels).
Getting there
7–8 min on foot from the west exit of Kamata Station (JR Keihin-Tohoku, Tokyu Ikegami and Tamagawa lines) — Nishi-Kamata 5-10-5, Ota-ku. From Haneda Airport ~15 min by Keikyu to Keikyu-Kamata then 15 min on foot, or bus to JR Kamata. ~10 min from Shinagawa by Keihin-Tohoku line. Small free car park.
Before you go
- As a communal bath there is no soap or shampoo — bring your own or buy at the shop.
- Payment is usually by ticket machine in cash — bring coins.
- Last entry is 30–60 minutes before closing.
Features
Sauna & wellness
Mood & scenery
Convenience
Price
Who with
Amenities
✔ Verified operating: 2026-09 Operating status and rates cross-checked against the official site and onsen guides (full source notes in Japanese on the JA page)
Prices and hours change. Check official sources before visiting.
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