The Shrouded Man
Origin
The story goes that one day the princess was kidnapped by bandits in the night. A small boy knew that if he didn't become the brave knight she would never be said. The boy faces great challenges and travels for a long time. He finally found the princess, rescued her and returned her to her kingdom. She made him her prince and they ruled side by side.
The truth is when the boy found the princess, he gave her his heart for the power to rule the kingdom. He left her in the Yellow Mountain and used his new power to enslave all the creatures of the land. By doing this act he became The Shrouded Man, the most feared sorcerer in all the land.
Creation
The Shrouded Man first appeared as the boy in the story in issue 1 of Canto but doesn't appear as the Shrouded Man until later in the series. His origin story is told in issue 6.
Major Story Arcs
If I only had a Heart
Canto seeks out the Shrouded Man to get a heart for The Tin Girl.
The Hallow Men
The Shrouded Man attempt to punish Canto and his people for Canto's actions earlier. He punishes Aulaura and her people for wanting to be free. The Shrouded Man also reveals to have trapped the princess in the Yellow Mountain as a guard for his real heart.