Photo/IllutrationKyosei Moriguchi, center, and classmates bathe in a traditional yuzu tub in Toyooka, Hyogo Prefecture, on Dec. 20, a day before the winter solstice. (Hisanori Fujimoto)

TOYOOKA, Hyogo Prefecture--It's the winter solstice, and what better way to mark the shortest day of the year than with a traditional soak with yuzu citrus fruit.

Public baths at this famed hot spring resort in western Japan fill their tubs with the tangy fruit each winter solstice, which this year fell on Dec. 21, as the custom is believed to ward off colds in the coming winter.

With 50 or so yuzu bobbing in the water, it “smelled sweet and slightly sour,” said Kyosei Moriguchi, a 6-year-old who joined five other classmates from his local preschool for a fragrant soak at Mandara-yu, well-known bathhouse here, on Dec. 20.

Because the facility is closed on Wednesdays, the yuzu special was offered a day early.

The city’s Kinosaki district is renowned for its hot springs.

Yuzu baths were offered at five premises on Dec. 21, excluding Mandara-yu and another bathhouse, Ichinoyu, which was also closed.