Anno-imo, a kind of orange-fleshed yam, has become quite popular in recent years as an ingredient in ice cream, custard pudding, miso and shochu liquor.

A little research revealed that the tuber's birthplace is Tanegashima, an island in Kagoshima Prefecture. I also found out that there is actually a village named Anno, where the yam harvest season was at its peak when I paid a visit.

Sweet potatoes, by and large, are oblong. But the Anno yams being dug up were round and fat like standard white potatoes.

"The skin is very delicate and bruises easily," said Suehiro Nagahama, 67, a plantation owner. "These spuds must never be tossed or piled up."

He handled his yams with great care, as if they were gems or porcelain.

According to local lore, the yam was brought to Tanegashima by a Japanese soldier returning from active service on the island of Sumatra during World War II.

For years, the tubers were grown on a very small scale in the Anno district. But they came into sudden fame about a decade ago, when their sweetness and moist texture became known nationwide through TV shows and magazines.

The crop acreage on the island has since grown 10-fold, and the number of producers has exceeded 500.

When cultivation spread beyond Kagoshima Prefecture but the yams were still being sold as Anno-imo, the identity of those originating from the island began to blur in the consumer market.

Alarmed by the likelihood of "genuine" Anno yams losing their competitiveness, the island's farmers sought survival by ensuring uniform high quality and developing sweeter cultivars.

The biggest "enemies" of Anno-imo are said to be sunburn during summer, bruising and frostbite--much like humans.

Market penetration efforts continue to render the Tanegashima Anno-imo brand as readily recognizable as other famed products, such as Hokkaido's Yubari cantaloupe and the Higashine cherry of Yamagata Prefecture.

A baked Anno-imo, split in half, reveals its vivid golden flesh, reminding me of tropical sunshine.

The yam is a "new treasure" of Tanegashima, the island where firearms were first introduced to Japan, and which is also home to the Tanegashima Space Center rocket launch pad.

--The Asahi Shimbun, Nov. 30

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Vox Populi, Vox Dei is a popular daily column that takes up a wide range of topics, including culture, arts and social trends and developments. Written by veteran Asahi Shimbun writers, the column provides useful perspectives on and insights into contemporary Japan and its culture.