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.

After Mash Burnedead's clash with Magia Lupus, the secret about his powers is now out in the open. The short-lived celebration ends when the Bureau of Magic summons Mash before an audience of Divine Visionaries, who collectively decree Mash should reap the consequences and die. However, an evil shadow organization called Innocent Zero hijacks the inquiry to demand that Mash be kept alive. Mash proves that he is capable of dealing with Innocent Zero, but the Divine Visionaries' verdict remains unchanged. Luckily, Mash finds unexpected allies in Divine Visionary Rayne Ames and Headmaster Wahlberg Baigan, and they successfully defer his execution until Innocent Zero is defeated. Mash is now allowed to live under one condition: he must be selected as the Divine Visionary candidate by the year's end.

Said to be humanity's natural enemy, formidable dragons that belong to an ancient bloodline roam the world. Only two ways prove effective to kill a dragon: freezing their blood with silverine—an aura that comes from silver weapons—or letting their bodies be incinerated by sunlight. Young hunter prodigy Leonica is accompanied by her close friend Ragna, who appears to lack the skills necessary in their profession. Moreover, many shun Ragna, considering him cursed because dragons always seem to attack him and slaughter his close ones. Nevertheless, Leonica sees potential in Ragna and gladly partners up with him. Likewise, Ragna feels certain that Leonica is immune to his misfortune thanks to her incredible strength. His confidence is shaken, however, when Ragna dreams of Leonica's death, believing this to be a prophecy. As the destined day arrives, he comes face-to-face with his future self, who bestows him enormous power and memories from the future to ensure Leonica's safety. In order to succeed, Ragna must join forces with a mysterious figure known as Crimson and eradicate all dragons for good.

Humanity was caught at a precipice a decade ago when the first gates—portals linked with other dimensions that harbor monsters immune to conventional weaponry—emerged around the world. Alongside the appearance of the gates, various humans were transformed into hunters and bestowed superhuman abilities. Responsible for entering the gates and clearing the dungeons within, many hunters chose to form guilds to secure their livelihoods. Sung Jin-Woo is an E-rank hunter dubbed as the weakest hunter of all mankind. While exploring a supposedly safe dungeon, he and his party encounter an unusual tunnel leading to a deeper area. Enticed by the prospect of treasure, the group presses forward, only to be confronted with horrors beyond their imagination. Miraculously, Jin-Woo survives the incident and soon finds that he now has access to an interface visible only to him. This mysterious system promises him the power he has long dreamed of—but everything comes at a price.