I Thought It Was Fairy Tail, but How Did I Become a Pirate After Leaving Seclusion?

Bad news: Travel to the Dark Age when dragons destroy the world! Good news: I have been bound to the Dragon King system for ten years! Chu Jin thought he was in Fairy Tail and practiced hard to avoid the Black Dragon King, perfecting the four dragon-slaying magics. Little did he know... An 800-meter blue dragon descended from the sky, and it turned out to be Kaido, the Four Emperors and One Hundred Beasts! Chu Jin was shocked to realize that he had been fighting with the air for ten years. In anger, he cut off the four emperors' dragon claws on the spot with a thunderous roar! The ten captains of Whitebeard landed on the island and were ruthlessly suppressed by him with one hand, but they didn't know... This terrifying combat power that is enough to overwhelm the new world is just the [Dragon Power] he has just unlocked! In the Age of Discovery, an invincible Dragon King with the Four Emperors at his feet has finally arrived!