Two new investigators at the Narcotics Control Department in Japan, Kurabayashi Hal and Eto Kai, struggle against drug dealers, gangs, murderers, psychopaths, and mysterious organizations.

Two newbies at the Narcotic Control Department in Japan, Haru and Kai, struggle against: drug dealers, gangs, murderers, psychopaths, mysterious organizations, and mad people in general. The gentle and caring one of the group, Kai, who has problems of his own, has the tendency of turning into a lethal killing machine in certain scenarios. The way he acts changes like that of a "switch". As the two do their job, answers of what is behind Kai's strange behavior and who exactly he is, is revealed.