An ordinary high schooler, Natsume Akira, meets with a road accident; when he wakes up, it's year 2030 and he finds himself aboard a smuggling vessel in the Tokyo Bay; his body is all mechanical, with only his brain remaining the way it was.

Shiga practically forces Akira to join the Tokyo MPD's Anti Ex-Arm Squad; Akira's all at sea, but he and Rokuoin Chikage go on patrol around Tokyo and meet a girl named Koharu.

The Counter Ex-Arm Squad heads to the Yokosuka Special Economic Zone to retrieve the EX-ARM held by the former president of the Mwange Republic, Jason Mraw, who has taken exile in Japan.

Akira connects to Iriya Heavy Industries' combat exoframe, Ogre; he uses it freely despite it being his first time and attacks Elmira's Bibot.

In the year 2014, a high school student who hates machines, Akira Natsume, wants to change himself for the better; he then gets run over by a truck.

An individual who calls themselves Auctioneer organizes an EX-ARM auction; criminal groups from all across the world flock to the Megafloat, hoping to get their hands on them.