A terrorist group invades a laboratory containing a deadly bacteria and destroys the lab with an explosion. They later announce via the internet they have gained possession of the bacteria and declare themselves to be the Red Siamese Cats, a terrorist group that was eradicated a decade ago.

Iori, taken from an orphanage by a family for domestic work, runs away and is adopted and raised by two young men. Ten years later, she crosses paths with her former step-sister, who is soon poisoned to death, Iori being the prime suspect.

Naito is serving time for his aggressive fundraising in the securities world, but returns to Osaka after completing his sentence. Although he wants to get clean, Oyodo Shinkin Bank has tasked Naito to raise funds.

The Badan Empire killed Ryo Murasame's older sister, and he had been cybernetically remodeled into ZX. However, he regained himself after an accident and stood up fearlessly.