Shigetoshi Kotari died Friday at the age of 28, six days after his violent 12-round split draw with Yamato Hata in Tokyo.

Following the bout at Korakuen Hall, Japan’s Kotari fell unconscious and was taken to a hospital for a brain bleed. Hata, too, was sent to the hospital to address the punishment from the fight. According to the UK’s Daily Express, the Japan Boxing Commission wrote in a press release that Kotari had a craniotomy – a surgery that removes part of the skull often in order to relieve pressure on or treat a brain injury – at the hospital.

In a social media post, the WBO wrote of Kotari: “A warrior in the ring. A fighter in spirit. Gone too soon.”

Before his 12-rounder with Hata, Kotari had fought exclusively in six- and eight-round bouts.

“Following the emergency surgery of Kotari, the Japan Boxing Commission are set to enforce changes by the Secretary-General Tsuyoshi Yasukawa,” The Sun wrote after Kotari’s death.

“OPBF title fights will now be 10 rounds, having switched away from the previous 12.”