Hiro is a black tender engine from Japan.
Hiro once lived on a railway in Japan. He was the strongest engine on his railway, and was famously known as the "Master of the Railway". He was eventually brought to Sodor, where he worked for many years. However, he began to show his age and the workmen did not have the necessary parts to repair him. To escape being scrapped, he was put on a siding, where he had to wait for the parts to come from his homeland. However, the parts never came and Hiro was all but forgotten.
Thomas eventually found him and, fearing Hiro would be scrapped if he was not Really Useful, promised to bring him back to his former glory while keeping him a secret from the Fat Controller. Thomas also had the rest of the Steam Team help in the restoration and Hiro quickly gained their friendship. After breaking down again while trying to avoid Spencer, Hiro was hidden away in another siding, where the engines visited him and kept him company.
When the Fat Controller found out about the situation, Hiro was brought to the Sodor Steamworks, where Victor oversaw his restoration. Once Hiro was restored, he helped Spencer after his accident and worked with him and Thomas to finish the Duke and Duchess's summer house. Despite everything, Hiro had grown homesick, so the Fat Controller arranged for him to be sent back to his homeland.