To earn money for his grandson's medical care, Hiraga Raizou signed up with a secret government organization of assassins. He's partnered up with a child-aged killer, Suzukaze Miharu, to take down the bad guys out of the law's reach. One criminal is at the top of Miharu's hit list, Musou Saburo, the crime kingpin of The Great Chain. He murdered her family and Miharu won't put away her guns until every link of his crime empire is destroyed! With Raizou's help, these two will tear through the Japan's criminal underworld!