In the year 2013, radio waves from outer space are picked up by scientists, proving to humans the existance of alien life meaning they were never alone on the earth. In the year 2015, The Earth Defense Force (EDF) which is a unified multinational army organization sponsored by nearly every country, is founded in case the extraterrestrials were proven to be hostile. But however, half of the people suggested the extraterrestrials would have nothing against them.
EDF ground forces are formed around three basic groups; Scout Teams, Ranger Teams, and Storm Teams, which fulfill Reconnaissance, infantry, and special ops functions, respectively supplied with the latest weapons, equipment, and is complete with thousands of soldiers stationed on every continent.
In the year 2017, first contact is performed when hundreds of UFOs proceed to hover over every major city across the globe, led by a massive mothership positioned over Tokyo, Japan. These extraterrestrials, who have been identified as "Ravagers", initially make no aggressive action towards humanity. As the EDF is mobilized, gigantic acid spitting ants start to appear and attack civilians. The protagonist is an unnamed Captain in Storm 1, a Japanese unit regarded as the best in the EDF, and helps exterminate the ants in Tokyo. Soon after, the UFOs start releasing more ants onto the ground, proving their hostile intentions. An air assault is attempted on the mothership, but is utterly destroyed by alien gunships. Giant mecha and spider-like insects are added to the fray, which contribute to already heavy losses. After weeks of brutal urban warfare, the surviving EDF forces abandon the cities and begin a guerrilla campaign in the rural areas.
While patrolling the countryside of Japan, Storm 1 is informed by command that an extensive alien nest is getting created underground. From this nest, the Ravagers will be able to spawn an infinite number of bugs and bypass EDF defenses. Intelligence provided by Scout Teams shows that a single alien Queen is at the center of the nest, and its destruction will stop the production of the rapidly multiplying bugs. Storm 1 assaults the nest with the help of all available Ranger Teams, and successfully humiliates the Queen.
A few days later, Storm 1 assists a Scout Team with monitoring the mothership, which has landed on the Japanese coast and appears dormant, damaged, and defenseless. Oddly, it is observed sucking in huge amounts of air and releasingcarbon dioxide, implying that the ship is more than a synthetic machine, and may be the hive intelligence controlling the Ravagers. Command orders the Teams to assault the mothership with heavy weapons, but it re-activates and wipes out the Scout Team.
Before the Ravager mothership retreats, it drops a massive four-legged mecha on the coast, which uses a powerful plasma cannon to assault EDF positions. Storm 1 destroys the mecha before it can cause too much harm, and later neutralizes several cyborg creatures of Godzilla proportions. While the Japanese contingent of the EDF continues to hold out, the rest of the world is soon overrun and enslaved. Japan stands as the last unoccupied territory.
All remaining insects and mechs on the ground make a beeline to the bombed-out ruins of Tokyo, where the mothership has stopped to repair and arm an enormous cannon, capable of destroying anything in its path. The remaining EDF forces move to block the Ravager advance so Storm 1 can destroy the mothership. In a climactic battle, Storm 1 opens fire on the weak spots the cannon has revealed, and the mothership crashes to the ground, exploding in a large fireball. The remaining Ravagers were discouraged. Soon, The Earth Defense Force then begins operations to free the occupied areas of Earth, and in the year 2018, they humiliated the remaining Ravagers. With the earth finally liberated, a collective chant of "EDF! EDF!" is heard across the globe which meant peace and harmony had been restored and justice prevailed.