Metalial Story is a Manga/Manhwa/Manhua in (English/Raw) language, Action series, english chapters have been translated and you can read them here.
Metalia, a world where mechanical creatures called the gears stroll. It was the so-called “machine hunters (collectors)” who hunted those who ruled the earth with mighty power. A boy now descends in Melzam, the largest city in Metaria. His name is Nill. He, with the right arm of the machine, had a secret. This is a story that looks for your fate.