Kastro is a fighter on the 200th floor of Heavens Arena and an Enhancement user.
He possesses considerable combat talent. After reaching the 200th floor, he lost his very first match to Hisoka. Although he was defeated, he managed to score 3 points, earning Hisoka's appreciation and subsequent baptism.
Following his defeat by Hisoka, relying on his own talent and exploration of Nen, he went on a winning streak, enduring two years of rigorous training with the sole objective of defeating Hisoka.
Chapter 197