1997 Japanese Best Two-Year-Old Colt award winner and Umamusume inspiration Grass Wonder has died at the age of 30, Thoroughbred Daily News reports.
The American-bred, Japanese-trained thoroughbred was diagnosed with age-related multiple organ failure at Japan’s Big Red Farm, where he had been spending his last years in retirement.
Grass Wonder debuted with an undefeated racing year in 1997, culminating in a record time victory at the Asahi Hai. He maintained an impressive career of G1 wins before retiring in 2000, including three consecutive grand prix victories in 1999 and back-to-back championships at the Arima Kinen.
“Our deepest condolences to a distinguished horse who left a significant achievement in Japanese horse racing,” a statement from Big Red Farm said. “Rest in peace, Grass Wonder.”
As one of the character inspirations for horse girl racing gacha game Umamusume: Pretty Derby, Grass Wonder is mourned by fans worldwide.
It is with heavy hearts that we share that Grass Wonder passed away on August 8.The legendary racehorse’s legacy serves as the inspiration for the character of the same name in Umamusume: Pretty Derby.We share our condolences to all the staff involved in Grass Wonder’s care.August 8, 2025
“The legendary racehorse’s legacy serves as the inspiration for the character of the same name in Umamusume: Pretty Derby,” Umamusume developer Cygames wrote on X. “We share our condolences to all the staff involved in Grass Wonder’s care.”
Grass Wonder was the final surviving Umamusume inspiration from Japan’s “Golden Generation”: a cohort of racehorses with exemplary careers who raced as Classic year competitors in 1998, eventually inspiring fellow Umamusume icons Special Week, El Condor Pasa, King Halo, and Seiun Sky.
He is survived by multiple generations of racehorses, having sired 736 winners from 1327 foals during his retirement. Among his offspring is 2008 Japan Cup champion Screen Hero, who in turn sired six-time G1 champion Maurice.
“Rest in peace, Grass Wonder,” wrote one fan on Reddit. “May you eat dandelions in heaven.”