Go read the first volume if you want to understand the story. I Don't Own Anything.

Y/n, was an ordinary person who lived a normal life. One faithful day, he was taken by the Celestial Dragons. As a slave he worked so hard that he found a devil fruit that no one has seen, but he knows what it is. He eats it and felt the power of the devil fruit flows through him. After seeing the suffering and feeling the pain from the tortures he manage to escape from the Celestial Dragons. On his journey he will be the one person who ate a rare fruit that let's him have the the power of elements, fell in love with the Pirate Empress and accepted her love, and friends with Monkey D. Luffy.