Tokyo 2039, Japan has fallen under the control of the multinational organization GHQ after the outbreak, in 2029, of an epidemic caused by a virus known as Apocalypse.
Shuu Ouma, wielder of "The Power of Kings", has led a rather secluded life at least until his encounter with Gai Tsusugami and Yuzuriha Inori, members of the resistance, thrusts him into the fight against the GHQ.