One Piece: Starting with Ryujin Jakka

Roya transmigrates into the world of One Piece, only to find himself trapped inside Doflamingo's Birdcage from the very beginning. Fortunately, he awakens a Sign-In System and immediately obtains the strongest fire-type Zanpakuto-Ryujin Jakka!!!

"Reduce all creation to ash, Ryujin Jakka."

With flames that towered into the heavens, he becomes renowned across the seas!

The Five Elders: "Damn it! Just who is this man who keeps standing in our way?!"

Sengoku: "This man definitely has some unspeakable scheme!"

Akainu: "His flames can actually hurt me!"

Red-Haired Shanks: "This is someone truly worth befriending!"

As he continues signing in on island after island, all manner of god-tier rewards emerge.

From this day onward, I am the strongest on the seas!