Hiro (寛) is a wise old Japanese engine, who is famously known as the "Master of the Railway". He regularly visits the North Western Railway.
Hiro was rebuilt as the prototype of the new D51 class in 1934. He soon proved to be the strongest engine on his railway, and able to haul any train with great efficiency. While Hiro himself was rather humble about it, many soon started to call him "The Master of the Railway". He made life long friendships with almost all the engines on his railway.
At the beginning of 1935, the North Western Railway on the Island of Sodor found itself needing more motive power, after Henry's "Flying Kipper" accident, which required him to be sent to Crewe for rebuilding. Officials on Hiro's railway heard about this, and decided to help the North Western, while at the same time seeing how its engines would cope in foreign environments. Sir Topham Hatt, unable to find a replacement for Henry on the Mainland, agreed. As such, Hiro was partially rebuilt to standard gauge and soon dispatched to Sodor on loan.
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 island, 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; he helped Spencer after an accident, despite Spencer previously trying to send Hiro to the smelter's yard.
Hiro is painted black with gold lining, boiler bands and fittings and red wheels. The number "51" is painted on the sides of his tender and the kanji 寛 is painted on the sides of his cab, both in white. He has gold nameplates with his name in black on his smoke deflectors.
- There is another member of his class with the same number as him.