The Demon King Fighting Style in Sailor Piece is a formidable melee combat style that excels at quickly clearing mobs. To unlock this style, players must locate an NPC resembling Anos Voldigoad on Academy Island. This NPC is positioned atop the castle and requires players to perform Air Jumps to reach him. To obtain the fighting style, players need several items: the 'Demon King' Title, 65 Calamity Seals, 12 Demonic Fragments, 6 Demonic Shards, 2 Destruction Eyes, and 1 Imperial Mark. The Demon King boss, which drops many of these items, can be summoned using Calamity Seals, with the number required varying based on the chosen difficulty. The boss has 350,000,000 health on Normal difficulty, and players can increase their drop rates by enhancing their Luck through various game mechanics. The Demon King Title provides a significant 60% damage boost, making it a valuable asset for players.