Two newbies at the Narcotic Control Department in Japan, Hal 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, are revealed.