Haru and Kai, two newcomers to Japan's Narcotic Control Department, battle drug traffickers, gangs, murders, psychopaths, strange groups, and insane people in general. Kai, the group's calm and loving member who has his own issues, has a tendency to flip into a lethal killing machine in certain situations. Like a "switch," he adjusts his behavior. As the two carry out their duties, the truth behind Kai's unusual conduct and who he is emerges.