Runny whites burst like jelly – Japan’s only “upside-down onsen tamago” hidden in a millennia-old hot spring town

▲ The specialty “upside-down onsen tamago” of Shirahama Onsen in Wakayama, Japan.

Reported and photographed by reporter Tsai Wen-jun / Japan

As the weather cools, it’s time for an onsen soak. Wakayama’s Shirahama Onsen, with a 1,300-year history and ranked among Japan’s three ancient hot springs, not only offers soul-warming waters but also serves the country’s only“upside-down onsen tamago”, a must-try snack and a beloved local souvenir.

▲ %? At around 3 minutes, Grandma Maekawa retrieves the onsen eggs with a bamboo basket.

Hidden down the winding alleys near Shirahama Onsen’s seaside is Kamakura Shop, the sole vendor of upside-down onsen tamago. Shop owner Grandma Maekawa explains,Normally, boiled onsen eggs have fully set whites and semi-runny yolks, but here, the upside-down version is just the opposite– cooked in steaming hot spring water at around 78 to 86 degrees Celsius for about 13 minutes, then shelled,the whites remain runny while the yolks inside are fully cooked, hence the name “upside-down onsen tamago.”

▲ Tap the eggshell gently with a small spoon before peeling.

▲ When peeled, the upside-down onsen tamago reveals runny whites with a bursting texture.

Peeling and eating come with their own tricks, says Grandma Maekawa. Before peeling, hold the egg in one hand and a spoon in the other, tapping the shell gently with the spoon’s tip in a circular motion until cracks appear. As she describes, the upside-down tamago’s whites stay runny, wobbling on the plate as if about to burst. To reach the yolk, suck the top layer of whites first. The yolk is slightly firmer than the whites, and interestingly, it continues to solidify over time – a quirky, delightful way to enjoy it.

▲ Finish the whites first to get to the yolk inside.

▲ The yolk gradually firms up over time.

Why has Kamakura Shop’s “upside-down onsen tamago” become a Shirahama Onsen specialty? Grandma Maekawa shares that it’s actually been a local favorite for ages, once sold by many shops, but they gradually closed. She’s the second-generation owner of Kamakura Shop, which originally operated in Shirarahama but relocated due to insufficient hot spring temperatures.

“The first owner was my elder sister. She actually wanted to close the shop,” Grandma Maekawa explains. With no successor, her sister applied to shut it down, but the government rejected the request, citing it as a “local specialty.” She eventually took over and has kept it running ever since.

▲ The exterior of Kamakura Shop.

Kamakura Shop’s “Upside-Down Onsen Tamago” (いでゆ反[?骏蕙矗)
Address: 2992, Shirahama-cho, Nishimuro-gun, Wakayama, Japan
Business hours: Approximately 9:30 AM to 5:00 PM, but times are irregular
Price: 90 yen each