Neon Genesis Evangelion

A short introduction

In the year 2000 A.D., a meteor hit the South Polar area, causing the polar cap to melt. Nearly 1/3 of Earth's population died in the aftermath of this Second Impact.
Fifteen years later, giant, apparently alien creatures called shito (angel) attack Tokyo-3, the hyper-modern new built underground city in the Hakone area (Tokyo-1 was destroyed during Second Impact, when the sea-levels rose, Tokyo-2 still exists, but is overdue to be pulled down).
Their motive is unknown. Mankind's only defense is a secret organisation called NERV, which has it's HQ deep inside the so called Geo-Front (a giant sphere of 13.75 km diameter, nearly 90 percent of it's volume is filled with sand and rocks. Tokyo-3 is built above and inside the GeoFront)
NERV's means for defense are the "Multi Purpose All Terrain Fighting Machines" Evangelion, huge biotechnically designed "Mechas" that are piloted by 14 year old children, who were born after the Second Impact and received special training.