After graduating high school, you decided to be a Demon Hunter just like your parents, who died on the hands of the most powerful Demons, The Zoldyck Family.

You got in to a Demon Prisoner, Where you need to gain strength and experience on how to handle such beast..

And there's where you meet him..

Prisoner 099 ♡

(This is an Age UP Killua)
Credits to the artist who draw the wonderful art above

Sorry for the stiff accent. English is not my first language.