The Eel Japan Built an Entire Summer Tradition Around

There is a reason unagi earns its own holiday in Japan. Glossy fillets of grilled eel, brushed with a sweet soy glaze and laid over a bed of warm rice, turn into one of the country's most comforting meals, the kind of dish people plan a special trip around.

Cooks in Japan prepare eel in two distinct styles. Kabayaki is the familiar version, butterflied and grilled while being basted repeatedly in a sweet tare sauce until it turns deep amber and caramelized. Shirayaki skips the glaze entirely, seasoning the eel with only a touch of salt so its natural flavor and smoky char come through.

Eating unagi during the hottest stretch of summer is a tradition known as Doyo no Ushi no Hi, a custom built around the belief that the rich, protein packed fish helps people push through the heat with their energy intact. Specialty eel restaurants fill up on this day every year, and the custom has endured for generations.

Among eel lovers, the area around Lake Hamana in Shizuoka Prefecture holds a special reputation. The region is widely considered home to some of the finest unagi in the country, and it has built an entire food culture, complete with specialist restaurants, around that reputation.

Wild eel populations have faced real pressure in recent decades, and Japan's Ministry of the Environment lists the Japanese eel as endangered. That challenge has pushed researchers and chefs alike to think carefully about the future of this beloved dish rather than take it for granted.

That effort is already paying off. In the spring of 2026, Yamada Suisan, working with Aeon Group, began the first commercial sales of kabayaki made entirely from eels raised from egg to adulthood in captivity, a milestone decades in the making that points toward a more sustainable future for one of Japan's most cherished comfort foods.