Grass Wonder, the legendary Japanese racehorse and beloved Umamusume: Pretty Derby character, has passed away at the age of 30. His death was announced on August 8 by Big Red Farm in Hokkaido, where he had spent his retirement years.

According to the statement, Grass Wonder died from multiple organ failure linked to aging. The stable shared that he had been in good health earlier this year, but his condition suddenly worsened the evening before his passing.

“We would like to express our heartfelt condolences to this great horse who made such a great contribution to Japanese horse racing. We pray for the repose of Grass Wonder’s soul,” Big Red Farm said in their announcement.

A Champion of the 1990s Racing Scene

Born on February 18, 1995, in the United States and raised in Japan, Grass Wonder quickly became a star in Japanese horse racing. He went undefeated in his juvenile year, winning four races in a row, including the 1997 Asahi Hai Futurity Stakes in record time.

His career highlights included:

• Back-to-back Arima Kinen victories (1998, 1999)
• 1999 Takarazuka Kinen win
• Nine victories out of 15 total races

Grass Wonder’s success earned him a reputation as one of Japan’s greatest middle- to long-distance runners of the late 1990s.

Legacy as a Stallion

After retiring in 2000, Grass Wonder enjoyed a successful stud career, siring multiple G1 winners. His most famous progeny include Screen Hero, who went on to sire champion stallion Maurice, as well as Sakura Mega Wonder, Earnestly, and Seiun Wonder.

Even in retirement, Grass Wonder remained a fan favorite. Through Japan’s Fresh Hay Bank crowdfunding program for retired racehorses, he received the largest amount of donated grass, almost 3,900 kilograms, even surpassing the famously adored Haru Urara.

Grass Wonder in Umamusume: Pretty Derby

Grass Wonder’s legacy extended beyond the racetrack into pop culture through Umamusume: Pretty Derby, where he was reimagined as a graceful, soft-spoken horse girl specializing in late-race surges.

Since the game’s Japanese launch in 2021, Grass Wonder has been a popular choice for players seeking a reliable medium-to-long-distance runner. Following the game’s global release on June 26, 2025, his in-game popularity further boosted interest in the real-life champion.

The official Umamusume: Pretty Derby social media accounts also shared statements from developer Cygames, expressing condolences for Grass Wonder’s passing and honoring the racehorse’s legacy as the inspiration behind the game’s beloved character.

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.

— Umamusume: Pretty Derby (@umamusume_eng) August 8, 2025

In the weeks before his passing, Grass Wonder became a trending topic among Umamusume: Pretty Derby fans after photos revealed he had grown noticeably plump in retirement.

GlassWander is voracious.
During racehorse, his groom skillfully managed weight.

After retirement, with no need for strict discipline,quickly became quite plump.

The post from Rena Maeda(voice actoress of Glass Wander), when she went to visit him.https://t.co/UKCN0IFCj4

— おすねこたろう (@Y_Tomcats100) August 6, 2025

A resurfaced 2018 post from Rena Maeda, the voice actress for Grass Wonder in the game, went viral, recounting her visit to the real-life champion. During her trip, Grass Wonder spent the entire time happily eating, with a particular fondness for dandelions.

Grass Wonder’s passing marks the end of an era for both horse racing and Umamusume fans. His impact as a champion, sire, and cultural icon ensures that his legacy will live on for decades to come.