One Piece: I Have a Sea King Doppelganger

With a Sea King clone, he devours Sea Kings night after night, sending energy back to his main body and growing stronger without end.

He explores the deep sea and the Calm Belt.

Years later, Klein has honed his physical combat skills, Observation Haki, Armament Haki, and Conqueror's Haki to their limits.

By then, he is known as the "Marines' ultimate weapon" and acknowledged as the World's Strongest Man!

Depending on how things go, Devil Fruits will be introduced midway through the story. The early chapters are all about hard-hitting fists and furious, blood-pumping action.

This book is also known as "I Became the Strongest Admiral with My Sea King Clone," "The Right Way to Use a Clone," and other titles.