The 27-year-old, who won gold in the halfpipe at the Beijing Olympics four years ago, was injured after crashing during a World Cup competition in Switzerland on Saturday.
He suffered a nosebleed and several scrapes around his mouth after hitting his face hard on the slope during his first run in the competition.
The Japanese Ski Association (SAJ) now states that Hirano has undergone several medical examinations and that he has suffered "several fractures and bruises."
According to SAJ, Hirano is expected to "gradually resume training as the swelling and pain subside" and he will undergo his rehabilitation in Japan.
Hirano also has two Olympic silver medals in halfpipe, from 2014 and 2018.
The Milan-Cortina Olympics begin on February 6.
