Spa & Hotel Nagomi

It's all natural, skin-friendly onsen water at this fancy Kamata spa, which boasts a women-only hot stone sauna area, regular saunas for both men and women, and a combined restaurant and 'relaxation area'. If you don't feel like lingering, consider opting for a one-hour 'speed' ticket (¥1,250 on weekdays, ¥1,550 on weekends and holidays).