In the year 2000, a giant meteor crashed in Antarctica. Upon impact, the ice continent completely melted down, resulting in the decimation of the Southern Hemisphere which wiped out more than half of the human population, rendered several species of animals extinct and severely altered the global climate. This catastrophe would later be known as The Second Impact.
Fifteen years later, while the world was still trying to recover from the Second Impact, strange entities known as Angels began to appear. Each of these Angels is capable of mass-destruction which the UN Forces cannot handle. Because of this, the task of counterattacking the Angels was passed to NERV, an elite organization based in Japan's technologically-advanced city/fortress of Tokyo-3.
Enter: Shinji Ikari, the 14-year-old son of NERV Commander Gendo Ikari. He has been chosen to pilot NERV's ultimate weapon known as Evangelion. Feeling a sense of distrust to his father, Shinji initially declined to pilot the EVA Unit-01. But upon seeing a severely injured Rei Ayanami assigned to take his place, and the inactive EVA suddenly protect him and Rei from fallen debris during an Angel attack, Shinji decided to pilot the EVA and receive his first taste of combat.
And so begins the saga of Neon Genesis Evangelion.