Hirata Runa, an eight-year-old Japanese performer who used the stage name Luna-chan, died at around 4 a.m. on Friday, Sept. 25, 2026, after suffering myocarditis — inflammation of the heart muscle — linked to an influenza infection, her agency said.
She had been on stage five days earlier. Hirata was a trainee with the DIANNA Project, a Nagoya-based talent program and girl-group scheme that develops and markets young J-pop “idols” based on their personality and public image. She was in her third year of primary school.
The announcement stunned supporters, who had seen her perform in apparent good health less than a week before her death.
A Final Message to Fans
Hirata appeared at the DIANNA Project’s Regular Live Vol.70 concert in Nagoya, Japan, on Sept. 20. Afterward, she posted a cheerful note of thanks to the people who had come to watch her.
“Thank you again today. It was so much fun,” she wrote, adding that she hoped the audience at the show’s third part would enjoy themselves too.
What the Agency Said
In a statement, the DIANNA Project said it regretted to announce that Hirata, one of its Nagoya trainees, had died of myocarditis associated with an influenza infection. The agency said that, following the wishes of her bereaved family, her wake and funeral were held with only close relatives present.
It also offered its deepest gratitude to the fans who had supported her and to everyone involved in her short career.
Family Asks Fans to Remember Her
Hirata’s family shared a tribute through her official account, writing that they were sorry to deliver such sudden news and confirming that she died at around 4 a.m. on Sept. 25. They thanked the fellow idols who had been close to her, the fans who followed her, the agency staff who helped make her an idol and everyone else connected to her.
“One third of Runa’s life was spent as an idol,” her family said, adding that she had loved everyone very much. They asked that supporters keep a place for her in their hearts and passed on her thanks for everything up to now.
Other Losses in Japanese Pop
Japanese pop has mourned other performers in recent years. Singer-actor Miho Nakayama, a figure in the early J-pop scene, was found dead at her home, and her agency, Big Apple, confirmed her death on Friday, Dec. 6, 2024. She was 54.
Nakayama was born March 1, 1970, in Tokyo and launched her entertainment career in 1985, balancing music and acting from the start. She went on to star in director Shunji Iwai’s 1995 romance “Love Letter,” which was released in the United States as “When I Close My Eyes.”
Myocarditis, the condition the DIANNA Project identified in Hirata’s case, is an inflammation of the heart muscle. Beyond the agency’s announcement, no further medical details or treatment history have been released.
With her funeral already held in private, the agency asked that the public respect the family’s feelings and refrain from making individual inquiries or media requests about her death, or from posting questions about it on social media.