Day Spa Near Me in Ota City: Tennen Onsen Heiwajima's 24-Hour Baths

Tennen Onsen Heiwajima is open 24 hours a day, every day, and ¥2,400 on a weekday buys up to seven hours of hot spring baths, saunas and reclining lounges with a towel and loungewear included. It occupies the second floor of Big Fun Heiwajima at 1-1-1 Heiwajima, Ota-ku, between Haneda Airport and central Tokyo. If you are searching day spa near me at an hour when everything else has shut, or killing time before an early flight, this is one of the few onsen in the city that will let you in at 3am.

The spring water is drawn from 2,000 metres below Heiwajima, at about 150 tonnes a day, and it is a sodium chloride water, salty on the lips and warming in the way that saline springs are. The facility sits on reclaimed land on Tokyo Bay, inside the Big Fun Heiwajima leisure complex that also houses Boat Race Heiwajima, the motorboat racing stadium.

The operator is Keikyu Kaihatsu, part of the Keikyu railway group whose line runs from Shinagawa to Haneda, which explains why the onsen markets itself so heavily to travellers with odd-hour flights.

The baths are grouped into themed zones. The Viewing Spa has a high-concentration carbonated bath, where tiny bubbles cling to your skin, facing a big screen. The Shining Spa has a jet bath for working on sore shoulders. There is also a high-temperature sauna for traditional sauna fans and a sun deck for cooling down in the open air.

The rock sauna rooms, where you lie on heated stones in loungewear, cost an extra ¥700. They are the most comfortable part of the place on a cold night, warm without the intensity of a Finnish sauna.

What makes Heiwajima work as an overnight stop is the resting space. The manga corner holds more than 10,000 volumes, and the Premium Lounge has reclining chairs where people sleep between baths. Lights stay low through the night, and many guests settle in with a pile of manga after midnight and wake up for a dawn soak.

It is not a hotel, and the reclining chairs are not beds. Light sleepers should bring earplugs. But for a few hours before a 6am flight from Haneda, it beats an airport bench.

The base ticket covers up to seven hours: ¥2,400 on weekdays and ¥2,900 on weekends and holidays, tax included, with a towel and loungewear. Each extra hour costs ¥400. If any part of your stay falls between 1:00 and 5:00, a late-night surcharge of ¥1,900 is added, so an overnight visit costs noticeably more than an afternoon one.

For treatments, shiatsu costs ¥3,500 for 30 minutes or ¥6,600 for an hour. The 30-minute session is enough to loosen your back after a long-haul flight. No reservation is needed for bathing, so you can walk in at any hour.

Heiwajima has a more flexible tattoo rule than most Tokyo onsen. Tattoos are refused in principle, but you may enter if every tattoo can be covered by four or fewer of the facility's own cover stickers, each 10 by 15 centimetres and sold for ¥260. Bigger pieces mean you will be turned away.

Children must come with a guardian, and anyone under 18 needs a guardian after 22:00. Between 2:30 and 9:30 the bathrooms are cleaned in rotation, so some tubs are closed during those hours. Bathing is nude and gender-separated. Wash at the showers first and keep towels out of the water.

The overnight crowd is a mix. You see travellers with a backpack and an early flight, office workers who missed the last train, shift workers coming off a night job, and friends who would rather soak than pay for a hotel room. Daytimes are quieter and older, with local regulars who come for the carbonated bath and a long nap.

Arrive around 22:00, before the late-night surcharge kicks in at 1:00 but late enough that you will not need the extra hours. Bathe first while every tub is open, since cleaning rotations start at 2:30. Then book the rock sauna, change into the loungewear and claim a reclining chair in the lounge by midnight.

Sleep until about 4:30, take a final quick soak in whichever bath is open, and leave by 5:00 for the first Keikyu trains towards the airport. Because your stay overlaps 1:00 to 5:00, budget ¥2,400 plus the ¥1,900 surcharge on a weekday, still far less than an airport hotel. Keep your boarding pass and passport in the locker, not in the lounge.

If you are not catching a flight, come in the afternoon instead. The seven-hour ticket without the surcharge is the better deal, the sun deck is pleasant in daylight, and the carbonated bath is quieter. Skip the overnight option unless you actually need somewhere to be at 4am. The reclining chairs are comfortable for a nap but not for a full night's sleep.

Heiwajima is not right next to a station. Keikyu Heiwajima Station is about fourteen minutes on foot and JR Omori Station about twenty-three. The spa recommends the ¥100 bus from either station, which is the sensible choice with luggage. Late at night, after buses stop, a short taxi from Omori is the simplest option.

The onsen occasionally closes for maintenance, and the next closure runs from 22:00 on 20 October to 11:00 on 23 October 2026, so do not plan a pre-flight night there on those dates. During daylight, Omori Furusato-no-Hamabe Park, an artificial beach on Tokyo Bay near Heiwajima, makes a pleasant walk before you bathe.

Address: Tennen Onsen Heiwajima, Big Fun Heiwajima 2F, 1-1-1 Heiwajima, Ota-ku, Tokyo. Phone: 03-3768-9121. Treatments 03-3768-9191. Hours: 24 hours, every day except maintenance closures. Price for up to seven hours ¥2,400 weekdays, ¥2,900 weekends, plus ¥1,900 between 1:00 and 5:00. Extra hours ¥400. Access: Keikyu Heiwajima Station, about fourteen minutes on foot, or the ¥100 bus from Omori. Tattoos only if covered by four stickers or fewer.