In a world where humanoid armored weapons known as Titatonostrider (TS for short) are used in warfare, troops from various countries converge on the island of Oahu, Hawaii, including Ao Isami of the Japan Ground Self-Defense Force and Lewis Smith of the United States Marine Corps. Isami and Smith cross paths during battle, but suddenly, their teams are attacked by an unknown enemy, scattering soldiers and sending their forces into disarray. In order to save their friends and survive on the deadly battlefield, they must fight with every ounce of courage and pride that they can muster.

(Source: Crunchyroll News, edited)