KASHIWA, CHIBA PREFECTURE >> Amid the seasonal heat, there’s such a craze for kakigori shaved ice that an increasing number of shops are turning to natural ice. Frozen slowly in cold weather, natural ice brings a distinctive flavor to this cooling treat, offered in an ever expanding variety of flavors and presentations.

Ryusuke Koike, director of the Japan Kakigori Association that comprises operators of kakigori shops and enthusiasts, took me to Mikazuki Hyo-katen in Kashiwa, Chiba Prefecture.

Shop manager Yoshiyuki Ikeda showed me a block of natural ice, which contained almost no air bubbles and was remarkably clear. His shop buys natural ice from a maker in Nikko, Tochigi Prefecture.

To produce natural ice, water from an underground source is poured into a pond in a mountainous area where it freezes in the severe cold of winter. There, watchful employees continuously remove dead leaves that fall on the ice and keep the surface clean. It takes about 10 to 20 days to complete the production of natural ice.

Ikeda’s kakigori looked like delicate feathers piled in many layers, and I found myself sighing in admiration at this beautiful dish.

From the nine flavors of syrup available, including matcha green tea, I chose plum. I put a scoop of the shaved natural ice into my mouth, and it melted away with a lightness I’d never experienced. The syrup had a sophisticated flavor with a mild sweetness and refreshing sourness.

“Natural ice is characterized by its fluffy texture,” Koike said. “This shop excels at preparing its own syrups, which are designed to make the flavor of the natural ice stand out, and at how it shaves the ice.”

Prices start at about 700 yen (about $6.60) for a bowl of kakigori.

Ikeda travels to Nikko every year to take part in work to cut out the natural ice. “The technique (for producing natural ice) has been established based on the knowledge of people in the past,” he said. “I want to carry on the culture of shaving natural ice — which locks in the essence of ‘winter’ — and enjoy its flavor.”

Japan’s history of shaved ice goes so far back that it’s even referred to in “The Pillow Book” by Sei Shonagon, a woman who served in the Imperial court of the Heian period (794 to the late 12th century). The aristocracy of the era had chunks of ice cut in winter and stored in icehouses to enjoy in summer.

It wasn’t until the Meiji period (1868-1912) that commoners began enjoying shaved ice.

Kirihara, a kakigori shop in Hayama, Kanagawa Prefecture, also uses natural ice. Manager Tomoko Nakamura buys fruits such as strawberries, tangerines and peaches to make the shop’s syrups, and customers are allowed to pour syrups over the ice themselves. The shop is open just from May through September.

“Kakigori is a summer staple,” Koike said. “I hope people visit various shops while paying attention to the ice itself.”