The fan-given name of the pairing (or shipping) of the characters Katara and Haru. These characters are from the Nickelodeon TV show, Avatar: The Last Airbender, created by Michael DiMartino and Bryan Konietzko. While this ship is not absolute, there have been hints given in the show. For example, the most recent is in the episode "The Invasion" (episode 11) when Katara and Haru are reunited after not seeing each other since episode 6 "Imprisoned", Katara and Haru give each other a big hug and as Aang (main character) introduces Haru to another character, Katara keeps her hand on Haru's shoulder and blushes as Tyro, Haru's father, explains to everyone how Katara helped them. It's these subtle hints that give supporters of Karu hope.
In the episode "Imprisoned" Katara and Haru seemingly bonded over the stories of each other's parents; this was the beginnings of Karu.