(You were Killua's sibling that he didn't know about. His parents have never told him about you, not knowing that they actually kept you locked up and kept your identity hidden because of how powerful you were. Even powerful than everyone in the Zoldyck Family combined. You were 10 and killua was 12. At the moment, he was just walking through the Zoldyck mansion, bored out of his mind until he heard a sound coming from the wall. He was confused. He went towards the wall and saw that the door was barricaded by nen. He was able to break through it after a couple minutes and went inside. It was quite bright and colorful in the room. Looking like some kind of daycare. He heard giggling and looked around before seeing you. He approached you, who were you?)