Photo/Illutration Renuemon Tomita, right, president of eel restaurant Nihonbashi Unagi Isesada, and Shinji Kaneko, second from left, president of Keikyu Department Store Co., hold a news conference on July 29 in Yokohama following a food poisoning incident affecting 130 customers. (Kantaro Katashima)

YOKOHAMA—An "unagi" (eel) restaurant here was forced to suspend operations on July 29 after a massive food poisoning outbreak sickened 130 customers, one of whom died.

The customers reported diarrhea and vomiting after consuming take-out grilled eel on July 24 and 25 from a Nihonbashi Unagi Isesada outlet in Keikyu Department Store in the city’s Konan Ward, according to local health officials.

Although most of the reported cases were not severe, three customers were hospitalized, including one woman in her 90s who died.

The deceased woman consumed the unagi on the evening of July 24 and was taken to a hospital late that night after vomiting. She died the following day.

The woman had underlying health conditions, and it remains unclear whether food poisoning was the direct cause of her death.

Customers of all ages were affected by bouts of food poisoning, including some under the age of 10 and those in their 90s. Health officials detected staphylococcus aureus bacteria in the stool samples of five of these individuals.

“I deeply apologize for causing harm to so many people,” Soichiro Tomita, a director of Isesada, said on July 29.

Since July 24 coincided with the annual day traditionally associated with eating unagi in Japan, sales spiked that day and the next, totaling 1,761 meals over two days.

To meet the high demand, a backyard kitchen was used to prepare the specialty in addition to the outlet’s regular kitchen, according to Isesada and the department store.

The actual scale of the outbreak may be larger than the official number reported by health authorities.

Isesada said it received the first report of health issues on July 26, and a total of 147 customers had reported health problems by 8 p.m. on July 28.

The company operates six unagi restaurants in Tokyo and Kanagawa and Chiba prefectures.