Fans of Grass Wonder, from both the racehorse and Umamusume communities, gather to mourn his passing.

Grass Wonder, a beloved Japanese racehorse, passed away of old age at 30 years old on August 8. The Thoroughbred was a racing icon of the late 1990s—but in recent years, he became best known as the inspiration for the character of the same name in the video game and anime, Umamusume: Pretty Derby.

The Umamusume universe reimagines the world of horse racing through anime girl characters, where players can collect various of them to participate in races. Developed by Cygames and released in February 2021, Umamusume: Pretty Derby steadily gained popularity and officially expanded into the global English-speaking market in June 2025.

The game has sparked increased interest in the horse racing world, with fans eagerly researching the real-life horses behind the characters. And Grass Wonder is one of them.

In Umamusume, Grass Wonder is portrayed as a shy, humble girl with chestnut hair and a white star on her forehead—mirroring the appearance of the real-life horse. She's known in the series as a gentle and easygoing competitor.

But in reality, Grass Wonder was even more remarkable. Born in 1995 in Kentucky, USA, he was trained and raced in Japan, where he became one of the top horses of his generation. He won 9 of his 15 races and placed second once, demonstrating consistent dominance.

Despite suffering an injury—a setback also depicted in the Umamusume storyline—Grass Wonder made a triumphant comeback, winning the prestigious Arima Kinen. After retiring in late 2000, he went on to father several notable horses, including Sakura Mega Wonder and Screen Hero.

On August 8, Grass Wonder died due to organ failure, which came alongside his old age. He died in peaceful care after 30 long years of a historic life. His legacy lives on in many parts of the world, one of them being the devoted Umamusume verse.