Gon is fully healed after a month passed. Killua buys tickets for them to watch Hisoka's fight. He tells Gon that Hisoka's fights are popular since his record is eight wins with three defeats and six of which are KOs. Hisoka's loses were due to him not showing up to fight and from all his fights he only lost four points. Three of them came from a fighter name Kastro. He is also Hisoka's opponent in the upcoming match. Since this match seems to be a fatal confrontation, Killua tells Gon that is the time to analyze Hisoka's techniques. Gon is about to get angry, but Wing appears behind them. He reminds them that watching a match is also considered learning Nen, and Gon still has a month before he can continue learning it. In other words, Gon is not allowed to watch Hisoka's match.
Killua goes to the match alone, but before the match begins, he tries to sneak into Kastro's room. Killua sees Kastro sitting in his chair, but suddenly Kastro approaches him from behind. Killua is shocked on what he has seen. Kastro then confronts Killua. The two chat and praise each other. Killua then asks Kastro about his technique, but Kastro refuses to answer for they might fight each other one day. The match with Hisoka and Kastro begins. After the two exchange words, Kastro makes his first move and attacks Hisoka. He is able to hit him and leaves Hisoka confused.