DC Kodansha Joker : One Operation Joker Vol. 1 Manga

The Joker like you've never seen him before...as a single father?! After a fateful encounter with Batman that results in the Dark Knight de-aging to a baby, Joker takes it upon himself to raise the child into the crusader of justice! But does the Clown Prince of Crime really understand what it means to be Batman--or, more importantly, what it means to raise a baby all by yourself? Everyone needs a babysitter who makes them laugh, right?

Written by Satoshi Miyagawa, Art and cover art by Keisuke Gotou