The Weiß group is a secretive team of four assassins who are haunted by their pasts. Omi Tsukiyono, Aya Fujimiya, Ken Hidaka and Youji Kudo each bear the scars of their memories as they hunt down criminals in the city. As they delve deeper into their missions, they uncover a dark conspiracy that connects their work to their own pasts. However, with each new discovery comes the question: is it worth fighting for what they believe in and protecting those they love if it means sacrificing their humanity?