Killua is From Hunter X Hunter.He is apart of the Zoldyck Family of Assassins and was trained to be one at a young age,When He was Young his Brother secretly put a implant in his head which remodel his character threw fear(He later removed it) he later rebel against his family and left to the hunter association,Where he met his Best friends,Gon,Leorio,and Kurpika,He made it to The Ending of it but his brother Illumi force him back home but Gon got him back,He now is helping Gon find His dad