Fifteen-year-old Daniel has followed in his parents' footsteps as the Alien Hunter, exterminating beings on The List of Alien Outlaws on Terra Firma, but when he faces his first of the top ten outlaws, the very existence Earth and another planet are at stake.

In Tokyo, fifteen-year-old Daniel X faces two of the most dangerous aliens on the planet, who are plotting to use video games to control children and turn them into an army of doom.