SEOUL--A Japanese member of popular South Korean female idol group Twice sparked a cross-border online feud by posting her feelings about the end of the Heisei Era (1989-2019).

“As a person born in the era, I feel somewhat sad that the Heisei Era is ending,” Sana wrote in Japanese on the group’s Instagram account. “But I want to say ‘otsukare-sama’ (Good work) to the era!!!”

Her post drew immediate criticism in South Korea.

“I think that Sana has mistaken Twice for a Japanese group,” one post said. “I hope she understands that history has not ended, but it is ongoing.”

The K-pop idol group consists of nine members. Five are South Korean, three are Japanese, and one is Taiwanese.

Given the group’s popularity, South Korean media reported on the matter.

One article carried the headline: “Sana’s Heisei (remark): ‘No problem’ vs. ‘careless.’”

For a few days, South Korean media covered topics about emperors and era names and connected them to Japan’s colonization of the Korean Peninsula from 1910 to 1945.

Some Japanese rushed to Sana’s defense.

One wrote: “It is cruel that a person who diligently learns the Korean language and works actively mainly in South Korea can’t talk about her mother country, Japan. I don’t understand why her words faced such harsh criticism. She didn’t even mention the emperor.”

In English, one poster wrote that Sana loves her own country, but this doesn’t mean she is taking sides in the historical dispute between the two nations.