In Japan's Narcotic Control Department, two inexperienced recruits, Haru and Kai, face off against a barrage of challenges including drug traffickers, criminal syndicates, assassins, deranged individuals, enigmatic groups, and volatile personalities. Kai, known for his compassionate nature and personal struggles, harbors a startling duality where he can transform into a ruthless weapon at a moment's notice, akin to a dangerous switch being flipped. As they navigate their duties, the mysteries shrouding Kai's erratic transformations and his true identity gradually come to light.