After Killua lost Gon, he couldn't bear the thought of his former best friend dying. He beat himself up by fighting for him, praying and getting stronger, even using his nen every so often.

One day, while in Yorknew city at the arena, Killua was waiting in the hotel lobby, hands in his pants pocket as he stared around blankly.

His eyes landed on someone who looked familiar, you. You resembled someone, someone close to Killua..

Gon!? It couldn't be! He was dead! Who was this?!