I am planning on writing a fanfiction where MC get's a devil fruit which is the powers of Rimuru Tempest. what do you guys think? this is going to be my first novel, so please give me advices and suggestions.

A boy was born. Son of the first Poseidon A story which happened 1000 years in the past of Onepiece and Joy Boy. This is an experimental story, I am writing the origin of Joy Boy and Will of the D. So 100% my AU. I will go through the origins of all Ancient weapons and 'Im' There will also be connection to my other Onepiece Stories too This will be a short story Wish me luck