Onsen Tamago Cafe Kusatsu

Onsen Tamago Cafe Kusatsu is a small cafe and snack stall situated near the Yubatake hot spring field in Kusatsu Onsen, Agatsuma District, Gunma, offering one of the most distinctive and low-cost local specialties of the resort town. The cafe's primary product is onsen tamago — eggs cooked not in a pan or pot but by immersion in Kusatsu's naturally acidic, sulphurous spring water, which maintains a temperature of approximately 70°C throughout the year. At this temperature, egg whites set to a soft, custard-like consistency while the yolks remain runny and intensely flavoured; the result is texturally distinct from either a hard-boiled or a standard soft-boiled egg. The eggs arrive in a small cup and are typically served with a ladle of warm dashi seasoned with light soy and mirin, making a miniature bowl that functions as a savoury snack or light meal addition. The Kusatsu lemon-flavoured soft-serve ice cream is a secondary item that draws visitors on warm days; the sharp citric tartness is locally characteristic. Hot spring steamed buns — made from dough leavened by steam from the spring vents — complete the short menu. The cafe operates primarily as a standing snack point for visitors walking the Yubatake and Sai-no-kawara circuit; seating is limited to a few stools. The setting, within a few metres of the primary Yubatake hot spring field with its wooden channels and sulphur-scented mist, provides an atmospheric context unique to Kusatsu.