In a superpowered society, there is nothing ordinary about evil anymore. Heroes, trained and licensed to protect and defend the public against supervillains, stand above all the rest. Not everyone can be a hero, however, and there are those who would use their powers to serve the people without legal sanction. But do they fight for justice in the shadows, or for reasons known only to themselves? Whatever they fight for, they are called...vigilantes.

As O'Clock and his accidental allies Tiger Bunny and The Rapper try to escape the riot in the underground arena, shadowy figures observe the chaos from afar. O'Clock takes on a hooded fighter who seems to be targeting him specifically. Back in the present day, Pop has been rescued, but Koichi and his friends have only a brief respite before the villainous Number 6 puts a terrifying new plan into action. In true vigilante fashion, Koichi must evade the law in order to protect Pop...