Robin Sena arrives in Japan to replace a fallen member of the STN-J. Engrossed in a witch hunt, the members of the team are unaware that this quiet 15-year-old is the new Hunter and brush her off. When they finally corner the Witch will they come to appreciate Robin's power?

The STN-J is called in by the local police when a dried corpse is found. When Robin finds a dead insect on the body the team goes on a hunt for a Witch who can control insects. They find that there were two previous victims found in the same condition. The cases point to a similar rash of deaths leading back hundreds of years. Apparently, all the dead are Witches. Is the STN-J dealing with an immortal who feeds on Witches?

When Robin's Vespa runs out of gas during a rainstorm, she is picked up by a kind-hearted motorist. Shortly after dropping Robin off, the woman is killed in a horrible accident. Upset over her death, Robin senses that a Witch may have been involved. Together with Amon, Robin pushes forward to uncover the truth.

When a suspected thief's wrecked car is pulled from the harbor, the STN-J suspect there is more going on then a mere accident. When the go to question the suspect, however, he flees in his car, crushing Karasuma's vehicle with a powerful blow in the process. But, was it the thief doing the crushing or a more sinister force?

After the most recent attacks, the Team keeps Robin under careful guard at the STN-J. The only one absent is Amon, who can't be reached. As they analyze the odd shell castings left from the attack at Robin's apartment, they find that only three people could have fired the Witch bullet at Robin. Unfortunately, the prime suspect has been dead for years. With growing uneasiness, they realize the only other person that could do this is someone very close to them all.

When Nagira brings in a couple to consult about the Fragment, Robin is unnerved by the woman's strange behavior. Her husband later explains that Robin resembles their missing daughter, whom they believe was Hunted by the Factory. Having being brought up without parents, the woman's reaction stirs up forgotten feelings within Robin and she begins to seek a relationship with the couple.

Robin and Amon finally confront Zaizen and learn the truth about Robin's existence. To Zaizen's surprise, instead of being traumatized, Robin is instead strengthened with resolve. Now Robin and Amon must stop Zainzen's final solution for the sake of both Witches and Humans alike.