Mamotte Shugogetten, Volume 5 Book

Let me tell you something about Killua Zoldyck.

He's a pretty little monster who is like aged 12 but then again he's a motherfu*kin beast. All you must know about him is that he is a talented baby assassin who just so isn't very fond of going round killing people. He attacks with his bare hands or his yo-yo (that's how badass the kid is). I keep saying kid but he ain't no ordinary one. His family are the Zoldycks who are this pretty cool family of assassins. The best assassins. His brothers are pretentions brats who don't share any affection for him. He is the strongest, most powerful kid in the family. He had no friends until he met Gon and that changed everything. The murderers didn't even allow Killua to have friends. Can you imagine that, going like ''yo mom I met a cool guy today he is extra chill'' and she replies ''u piece of s*it don't you know any better than making acquaintance with other people''. He's imune to pain and poison. He's basically the boss.
The best manga character I've ever come across.