A Russian spy is found murdered in Japan, with the only clue to the
reasons for his death being a memory chip he managed to hide from his
murderer. The Third-I branch of the Public Security Intelligence Agency
recruit Fujimaru Takagi, a brilliant hacker known as "Falcon", to
decode the chip, which contains a video file documenting a viral
outbreak in Russia where thousands are killed, known as the Christmas
Massacre.
Things become further complicated when Fujimura's father, a high
ranking official within Third-I, is falsely accused of murdering his
superior when he receives further information related to the Christmas
Massacre, and the code name "Bloody Monday".
The terrorist Maya Orihara, who was responsible for the incident in
Russia, is now in Tokyo in order to recover the memory stick to stop
Third-I from knowing the truth of a terrorist plot in Japan. She goes
under cover as a teacher at Fujimaru Takagi's High School. From there it
becomes difficult for Fujimaru to determine who he can trust as he uses
his high-level hacking skills to try to save the country and unravel
the mystery of Bloody Monday and the cult behind it.