As Japan faces its hottest summer in history, a sharp decline in the catch of sea urchin in the country's north has placed the spiny delicacy further beyond reach for many consumers already strained by high food costs.

On Hokkaido's Rishiri Island, restaurants offer a rice bowl with 100 grams of bafun sea urchin — renowned for its rich sweetness — at a record ¥15,000 to ¥18,000 ($100 to $120), roughly double its price several years ago.

"Everyone is shocked when they see the price," said Kimiko Sato, owner of the Sato Shokudo restaurant, across from Rishiri's Oshidomari ferry terminal, which her family has run for more than 50 years.