It appears this was likely a major mistake by this restaurant in Japan, but the Korean couple that was poisoned by the bleach are claiming it was a hate crime:

The Korean government has requested Japanese authorities to conduct a swift and fair investigation into a case where a Korean national was served water containing bleach at a restaurant in Tokyo. 

“We contacted the local police station as soon as we were notified about the incident,” said an official at the Ministry of Foreign Affairs, adding that the victim reported the case to the Korean Embassy in Tokyo on Sept. 6.

The official noted, “The Japanese police responded that they will do so, but refused to share details of the investigation at this stage.”

The official also said the ministry was informed that the restaurant’s operations were suspended for four days in relation to the incident.

On Aug. 31, a Korean woman surnamed Kang and her Japanese husband visited a high-end restaurant, famous for tempura, located in a department store in Tokyo’s Ginza. 

The couple was served two cups of drinking water upon their request, but after taking the first sip, Kang noticed a strange odor from the water.

“After the second sip, my throat began to hurt so bad I couldn’t even talk properly,” she said during an interview with local broadcaster JTBC, Monday.

She made complaints about the water immediately to the waitress and the manager, but they attempted to take the cup back without offering any explanation. Only after her husband strongly protested to the chef, the waitress admitted that the water was poured from a bottle of water containing bleach.

After showing symptoms of stomach pain and nausea, the victim was taken to a nearby hospital where she was diagnosed with acute food poisoning.

Korea Times

You can read more at the link where the couple is claiming this was a hate crime.