Former Japan international Naoki Matsuda has died in hospital in Matsumoto aged 34.
The defender collapsed at training with third division J-League club Matsumoto Yamaga on Tuesday and was rushed to hospital after falling into a coma because of a heart attack.
He was put on life support but passed away, leaving Japan football fans to mourn the loss of a player who represented the Blue Samurai on 40 occasions.
Japan coach Alberto Zaccheroni did not know Matsuda directly but paid tribute to the former Yokohama Marinos star.
"I never got to know Matsuda directly but knew what a great player he was having watched him in the J-League last year," he said.
Japan Football Association technical director Hiromi Hara was in shock when he heard the news.
"I can't believe it," said Hara.
"I have managed or coached teams playing against him many times and know what a big presence he had."