Dave Hirao, the leader and vocalist of the band The Golden Cups, died on Monday morning at a Yokohama hospital. He was 63.

The singer, whose real name was Tokimune Hirao, was feeling unwell and went to the doctor three weeks ago. It was discovered that he had esophageal cancer, and he immediately opted to have surgery on October 20. The operation lasted 10 hours but was successful. He had reportedly returned to his energetic self while recovering at the hospital, and was last seen healthy early on Monday morning. Just an hour later, a nurse discovered him unconscious, and he was unable to be saved.

The Golden Cups were a successful band in the 1960s, part of the Group Sounds movement. Its members included keyboardist Mickey Yoshino, who went on to lead the band Godiego. The band reformed in 2004 to occasionally play live shows. They had been scheduled to perform on the 28th of this month.