Nen: the hidden source of energy and potential that runs through everyone, and gives those that master it a source of great power. Inside Nen is the potential for limitless light and limitless darkness. The Hunter Association has arisen to control access to it. Hunters come in many shapes and forms, and with many different appetites - but all of them have learned to master Nen, and use it to chase wealth, power, and their dreams. The greatest and most powerful Hunter is Isaac Netero, chairman of the Hunter Association. Decades ago he sealed away Jed, a Hunter who had mastered the use of On, the dark "shadow" of Nen. Now On users have reappeared at the Heaven's Arena "Battle Olympia" tournament. For Netero, this is the last mission: to protect the Association and the world from a threat driven by hatred and the thirst for revenge. And he's going to need all the help he can get in order to succeed.Some tens of years ago, chairman of the Hunters Association Isaac Netero sealed away Jed, a man representing the Shadow of the association that had began to make use of the power On. On, being another side of the coin of Nen, derives its power from the users pure hatred at the cost of their life. Although he thought he had sealed Jed and On away, a team of On-using warriors appears at Heavens Arenas Battle Olympia Tournament. Gon and Killua, who had come to cheer on Zushi, along with Kurapika, who attends the tournament to protect his boss Neon, are forced to find the source of a violent invasion of the tower and defeat it. However, this may not be so easy, as their foes use the power of hatred as they wish for the death of all Hunters.