On February 3rd, 2004, a 15 mile long, 5 mile wide tower fell on Earth from out of nowhere. It devastated the entire planet and has killed over 65% of the total population. The tower holds all kinds of evil and acts like a Pandora's Box to the entire world. Evil species called 'Angreifers' ravage the world as the Mankind Restoration Conglomerate (MRC) recruit the strongest warriors on Earth as fast as they can to protect their homeland.  Kaori Tokuda was involved in a fatal car accident two years ago, and was in a comatose state ever since. Now awake and depressed, she finds out the world has changed in 2 years. Kaori and her long-time best friend, Kaede Chuyoshi, go back to school to do mock exams. They soon hear that an unidentified flying object entered Earth's exosphere, but was soon thought to be an asteroid. 2 hours later, what people thought to be an asteroid was in fact a tower, and crashed onto Earth, setting Angreifers loose and starting the First Reign, the extermination of humanity.