One Blade Burns the Sea, Sign-In to Ascend Godhood

Roia transmigrated into the world of One Piece, only to be trapped inside Doflamingo’s deadly Birdcage the moment he arrived. At the brink of death, the Sign-In System awakened. His starting reward: the supreme flame zanpakutō — Ryūjin Jakka! "All creation, reduced to ash — Ryūjin Jakka." Towering flames swept across every battlefield. Even Akainu’s magma could not withstand a single slash. The Five Elders deemed him a grave threat; Sengoku held deep wariness of his power, while Shanks sought to forge an alliance with him. He traveled across every island along the Grand Line to complete daily sign-ins, unlocking an endless stream of god-tier abilities. Once his blazing fire engulfs all four seas, he alone shall stand as the undisputed strongest of the entire ocean!