Hiro is a Japanese engine based of the real D-51 engine.
He attended Henry and Gordon’s wedding in Tied knots and wedding bells
- Season 1 - The Old Recipe (cameo) and Hiro Goes Home
- Season 4 - Hooray for Hiro
- Season 5 - Something Smells Fishy (cameo)
- Season 6 - Hank's State: Worried (mentioned, seen in flashback)
He will appear in Season 7.