One Piece : Invincible

My name is Chad Cain, a transmigrator, Luffy's third older brother and just an ordinary pink-haired teenager. I used to have a cushy Marine job, thanks to my grandfather-grandson relationship with Garp, I could have easily coasted like Kizaru, punching in and out while working a desk job as a low-ranking clerk. But everything changed when I took Garp to that island and ate that fruit. Where did this ridiculous rumor even come from? What's this about me being the illegitimate child of two Emperors, Kaido and Big Mom? — Description from novelcodex.org