TOKYO (Kyodo) -- Former WBC minimumweight champion Yudai Shigeoka announced his retirement Wednesday to offer his support to his younger brother Ginjiro Shigeoka, who remains unconscious following his bout on May 24 but is no longer in a life-threatening condition.

Ginjiro, a 25-year-old former IBF minimumweight champion, underwent a craniotomy to nurse a right subdural hematoma after his split decision loss to Filipino champ Pedro Taduran in a title match in Osaka.

"Together with Gin, we'll flourish in a new field," the 28-year-old Yudai wrote on his Instagram. "I've managed to come this far because Gin was with me."

"It's my duty as an older brother to brighten his life from here on."

Southpaw Yudai won his WBC belt in October 2023, but he failed to defend it in March 2024 and lost a world title bout this March. He ends his career with a 9-2 record with five knockout wins.

Ginjiro has passed the critical point and has been transferred to a hospital in his native Kumamoto Prefecture with a view to starting his rehabilitation in earnest, according to the Japan Boxing Commission.