Two Enemies is Chapter 23 of the Hunter × Hunter manga, written and illustrated by Yoshihiro Togashi.
Summary
The lottery will determine the hunter and the prey. The examinees will pick a card inside the box, whoever has the number plate of the number you have then he or she will become your prey. All you have to do is grab the number plate of your prey. All examinees need 6 points in order to pass. The examinees own plate number costs 3 points while the prey's plate number also costs 3 points. If you fail to get your prey's plate, then you can steal the other examinees plate number which costs only 1 point.
The examinees are the taken to Zevil Island, accompanied by Kara. Killua approaches Gon and asks him which number did he pick. They decided to show each other. In Killua's surprise, Gon pick Hisoka's number. Killua sks Gon if he knows number 199, the number he pick. He claims that everyone had already hidden their plate numbers making it difficult for him. Gon hopes in getting Hisoka's number, all he has to do is to steal it so that means Gon has a chance. Killua leaves and tells Gon to stay alive.
In Zevil Island, the examinees take turns on getting to the island. There is a 2 minute separation before the next examinee may leave. They have exactly one week to spend their time on the island. Gon immediately looks for Hisoka, but he feels that someone is watching him from afar. Gretta is shown to be hiding on the trees and stalking Gon, who happens to be his prey.