In 2013, radio waves from deep space are received by scientists, revealing the existence of
extraterrestrial life. Two years later, the Earth Defense Force, a unified multinational military organization, is established in case the aliens are hostile. In 2017, first contact is made when hundreds of
unidentified flying objects suddenly arrive and hover over major cities across the globe, led by a massive
mothership positioned over
Tokyo. As the EDF is mobilized, giant acid-spitting insects resembling ants begin assaulting many civilians. The main character is an unnamed Captain in Storm 1, a
Japanese unit regarded as the EDF's best. An air assault by the EDF is attempted on the mothership, but the plan is thwarted by alien UFO gunships. This operation is deemed a failure, resulting in the surviving EDF forces abandoning the cities to begin a guerrilla campaign in rural areas. While patrolling the Japanese countryside, Storm 1 is informed by command that an extensive alien nest is being built underground. From this nest, the aliens 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 kills 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 releasing carbon dioxide, implying that the ship is more than a synthetic machine, and may be the
hive intelligence controlling the aliens. Command orders the Teams to assault the mothership with heavy weapons, but the ship re-activates and wipes out the Scout Team. Before the alien 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
kaiju-like cyborg creatures. 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 alien advance so Storm 1 can destroy the mothership. Storm 1 focuses fire on the mothership and destroys it. The remaining alien forces become disorganized and flee. ==PlayStation Vita port==