Suzaku Toshiba, an ordinary high school student, gets caught up in an alien invasion when his new classmate Mana Kurosaki turns out to be an alien in disguise. Mana tries to kill Suzaku, revealing that he is the son of someone who killed her parents and possesses the power of the "World Killing Power Destroyer" that the aliens want. As the aliens attack and kidnap people, including Suzaku's family, Suzaku suddenly transforms into a powerful female entity called Sakura Yamigawa. With her shadow powers, Sakura is able to deflect the aliens' attacks and rescue the kidnapped people. Though the aliens retreat for now, their leader vows to return. Sakura promises to keep fighting to protect humanity from the alien threat. The story sets up an epic conflict between the newly empowered Sakura/Suzaku and the technologically advanced aliens who want to wipe out humanity, with Suzaku's friends and family also getting caught in the middle of this interstellar war.