What happened to legendary racehorse and Umamusume icon Grass Wonder? Details are explored as he dies at 30

The racing community and anime fans alike were stunned to learn that Grass Wonder, the American-born racehorse turned Umamusume icon, has died at Big Red Farm in Hokkaido on August 5, 2025. He was 30. Farm manager Hiroshi Tanaka announced that the beloved stallion succumbed to multiple organ failure, a natural consequence of his remarkable age.

Grass Wonder first captured headlines as a flashy two-year-old, storming home to victory in the 1997 Asahi Hai Futurity Stakes. After recovering from a serious leg injury, he roared back in 1999 to claim both the Takarazuka Kinen and the Arima Kinen, thrilling crowds with his trademark late surge. Retired to stud in 2000, he sired several winners before settling into a serene retirement in 2015. Years later, his legend found new life in Umamusume: Pretty Derby, where his calm strength inspired a reflective, poetry-spouting trainee character, bridging generations of racing buffs and anime devotees.

Grass Wonder dies at 30: A champion remembered on track and screen

Grass Wonder slipped away quietly on August 5, succumbing to multiple organ failure at Big Red Farm in Hokkaido, where he had spent his golden years after breeding duties. At 30, he was one of the oldest living champions, and his passing prompted farm manager Hiroshi Tanaka to reflect,

“He wasn’t just another stallion here, he had character. Even in retirement, he held himself with that same quiet pride he wore at the post.”

On the turf, Grass Wonder was the horse who refused to be counted out. In 1999, he stunned spectators by overtaking Japan’s finest—first in the Takarazuka Kinen, then again in the Arima Kinen—despite a serious leg injury that had sidelined him the season before. Veteran racecaller Keiko Suzuki still recalls the roar of the crowd as he powered past the leader:

“It wasn’t just his speed; it was that steely determination in his eyes.”

After hanging up his racing shoes, Grass Wonder sired a handful of winners before retiring to the pasture in 2015. But it was Umamusume: Pretty Derby, the wildly popular anime and mobile game that introduced him to fans who’d never set foot at a racetrack. In the series, his counterpart is a reflective, poetry-spouting trainee whose calm under pressure echoes the real horse’s temperament. Series producer Yuki Kato noted, “We wanted to capture his essence—his dignity and unspoken strength.”

Grass Wonder’s story is a rare bridge between sport and pop culture. He may have raced his last furlong, but both turf enthusiasts and anime fans will long remember the horse who became a quiet legend in two very different worlds.