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.

Kumiko Ijima who is one of Nube's students recognizes that a man in a local park is really a criminal wanted for murder when she remembers drawing his face from the wanted photos posted by the police. Kumiko warns her classmate Kyoko while at the same time the man discovers the drawing with the name initials "K.I." written on Kumiko's drawing portfolio and briefly sees that Kumiko wears a red ribbon in her hair. The cops chase the criminal who crashes his car into a seal where a demon takes control over his soul. The demon is now on a killing rampage to find any girl that wears a red ribbon whose name initials are "K.I.". (Source: ANN)

New student comes to Nube class. His name is Jun and he's a lonely boy who loves clowns very much. His only friend is a Pierre - clown in the mirror. And one night Pierre gives Jun a mask with strange abilities. At that point Jun starts to act strange and lot of accidents occur in the school.

When Nube and his class arrive at a small island to carry out beach activities, they heard a forbodding tale from an old man residing on the island. Legend has it that there is a creature known as the sea spider in the open seas around the island. When the creature is past 200 years old, it will turn into a monster and devour humans to satisfy its appetite. However, curiousity kills the cat and Yukime decides to pursue the authenticity of the legend. And then, a girl suddenly appears on the beach. Possessed with a strange charm, she immediately attracts Hiroshi's attention and overcomes him. Soon later, strange things start to happen to the others whereby Kyoko and Ritsuko-sensei got attacked under strange circumstances. The true identity behind the mysterious girl is questioned and the legend behind the sea creature seems to be true after all.