Hiro is a wise Japanese engine, who is famously known as the "Master of the Railway".
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 break down 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 of Boxford's summer house. Despite everything, Hiro had grown homesick, so the Fat Controller arranged for him to be sent back to his homeland.
Hiro eventually came back to Sodor to help the engines with the summer holiday traffic. Upon his arrival, Hiro went to the Steamworks to be examined and then went to Knapford station for his welcome party, which was almost delayed as Thomas was trying to find a welcome present for Hiro instead of telling the other engines about the party. But, Hiro told Thomas that having his friends at the party was the best welcome present. During his visit, Hiro told Thomas to take the load of bees through the woods, which Thomas ignored. However, Thomas took Hiro's advice after taking Hiro's flower truck to get the bees back to their hives. Later on, Hiro saw the Fat Controller and assumed he was too busy to give orders to his engines. So, he tried to help the Fat Controller by giving out the orders - but he only succeeded in becoming "Master of the Muddle". However, he made up for his mistakes by telling the engines to go to Knapford and await orders from the Fat Controller.
Hiro is still on loan to the Fat Controller. He saw Jobi Wood being delivered to the Docks and told Thomas about where it came from. He later pushed Henry to the Steamworks to have his side-rods repaired and when Hiro became homesick, Thomas took him to Misty Island, which reminded Hiro of his home.
Later on Hiro, along with Henry, took on some bad coal. While Henry did not want to carry on, Hiro was determined to get the job done. He did so, but during his next job of transporting girders with Henry, Hiro broke down and Henry had to come to the rescue.
Once, Diesel tried to teach him how to handle trucks, suggesting that the only way of tackling them was with force. However, Hiro insisted that being gentle was the best policy. However, when Diesel stuck to his own belief, he ended up causing Hiro's milk churns to spill over the Fat Controller — twice! After this, Diesel was found out and Hiro was tasked with teaching Diesel the correct way to treat trucks!
In the eighteenth season, he stopped Caitlin while he was on the Mainland after she accidentally took Annie and Clarabel and brought them back to Thomas on Sodor. Later, he helped clear the tracks so Connor could deliver the last of his passengers on Christmas Eve and nearly mistook Harold for Santa Claus.
After six years of virtually no accidents at all, Hiro derailed at a bend when he hit some pipes which came loose from Thomas' train. With his left side severely damaged, he was sent to the Steamworks to be repaired again. Thomas, believing that there were no spare parts for him, went to Hiro's old hideout, only to get lost. When Thomas was found, Hiro revealed that the Fat Controller had bought plenty of spare parts for him and that he was already repaired.
In the twentieth season, at Christmas, he had the job of taking the mail to the Mainland to be delivered to the North Pole. Percy was supposed to bring more mail, but got stuck in a snowdrift, meaning Hiro had to leave without it. Harold managed to catch up to him and give him the rest of the mail.
He later went to The Great Railway Show to compete in the Strongest Engine Race, representing his home country, Japan.
Hiro is an old steam engine who has been on Sodor for a very long time and was originally known as the "Master of the Railway". He is grand, masterful, mature, wise, very dignified, enormously kind and is able to find good in any engine he meets. He has an appreciation for serenity and order and often thinks fondly of his homeland, far away, where he was once one of the strongest engines. Hiro fell victim to neglect when waiting upon parts to arrive for him from his home country, when he began to break down and became lost. He was eventually rediscovered by Thomas, who, despite some problems in worrying about sharing the discovery of Hiro with the Fat Controller, helped Hiro to be fully restored to his former glory. Hiro continues to be gentle, wise and graceful, as well as a useful engine on the railway and a good friend to the other engines, especially Thomas. He does not appear to hold a grudge; in his first appearance, he helped Spencer after an accident, despite Spencer previously trying to send Hiro to the smelter's yard.
Hiro is based on a Japanese National Railways (JNR) Class D51 2-8-2 "Mikado" built by Kawasaki, populary known as the "Degoichi" in Japan. In addition to Japan, members of this class worked in South Korea, China, Taiwan and the USSR. Though Hiro's number is a reference to his basis name, there is a D51 with the number 51. However, unlike Hiro, the real engine is an earlier build of the D51 class, with its dome flush with its funnel. It is preserved at Torokko Saga Station in Kyoto, Japan. Hiro is standard gauge, while the real D51s were built for 3'6" gauge (cape gauge), though the two examples of his class exported to South Korea were built to standard gauge. Over 170 of these engines are preserved.
Hiro is painted black with gold lining, boiler bands and fittings and red wheels. He has the number "51" painted on the sides of his tender in white and he has gold nameplates, with his name in black, on the sides of his smoke deflectors. His "patchwork" colour scheme consists of a blue boiler, a green right smoke deflector, a purple left smoke deflector, a brown dome, a green piston and rusty-red coloured wheels.