[5][6] Ayumu Hirano was born and raised in the small coastal city of Murakami in Niigata Prefecture, situated in a rather snowy area in Japan.

At the age of 12, the sixth-grader was not officially allowed to enter the open division of the event, where his mentor Kazuhiro Kokubo would win gold, and his brother Eiju would take seventh place.

In 2012, he was invited to the Burton High Fives, an open event held in New Zealand to win the gold at the age of 13.

In 2013, he was invited to compete in the Winter X Games in Aspen, Colorado, snowboarding's biggest non-Olympic stage, where he won silver in the halfpipe behind Shaun White, who explained: "The Japanese rider who got second is 14 years old.

[8] In 2018, Hirano became the first Japanese snowboarder who won at Winter X Games Aspen after landing the first-ever back-to-back double cork 1440s in Halfpipe history.

[9] Hirano again took the silver in the half pipe at the 2018 Winter Olympics in PyeongChang, with Shaun White of the U.S. taking the gold and Scotty James of Australia garnering the bronze.

Hirano landed the first triple cork in halfpipe competition history at the 2021 Dew Tour at Copper Mountain.

Kokubo has been mentoring Hirano since 2011 and was assigned as the official technical coach for the Japanese national snowboarder team in 2013 by the Ski Association of Japan to support them in the 2012–2013 season.