Inasayama Onsen Fuku-no-Yu, Nagasaki
A large day spa where you can gaze at Nagasaki's night view — ranked among the 'new three great night views of the world' — from the bath. Built on the slope of Mt Inasa, its rooftop open-air bath looks down over Nagasaki harbour and the city, which turns into a sea of lights after sunset. The alkaline simple water fills carbonated, electric and jet baths; there are several saunas and cold plunges, six family baths with rest rooms, a suite of bedrock baths (extra charge) and a self-service canteen. Adults ¥850 on weekdays, ¥900 on weekends and holidays, children ¥450; family baths from ¥3,000 for 60 minutes. Open late, 09:30–01:00 (until 02:00 on Fridays, Saturdays and holiday eves; last entry 30 minutes before), with no fixed closing days apart from maintenance. A free shuttle bus runs from JR Nagasaki Station (about 20 minutes), a big plus without a car. The classic plan pairs it with the Inasayama ropeway: see the view from the summit, then soak. 320 parking spaces; payment is mainly cash.