New Chitose Airport Onsen (Domestic Terminal 4F, Natural Hot Spring, Open 23 Hours)

A natural hot spring on Domestic 4F, open 23 hours from 10:00 to 9:00 the next day (last entry 7:30). Admission is ¥2,600 for adults, ¥1,300 for elementary school children and free for preschool children (bathing plus a yukata and towel set). After 1:00 at night, a late-night fee (adults ¥2,000, elementary school children ¥1,000) is added, and staying until morning is a flat ¥4,600. A morning bath (5:00–8:00) is ¥1,300 for adults. You can rest or nap in the relaxation room, and there are also twin rooms for overnight stays (11 rooms). You cannot stay overnight in the airport building, so if you want to spend the night at the airport, this is the only option. First come, first served with no reservations; how crowded it is is shown on the official website. People with tattoos cannot enter, and groups made up only of people under 18 are not admitted.