Full Metal Panic! is a series of short stories, novels, anime and manga, created by Shoji Gato and implemented since 1997.

plot
We are in an alternate universe similar to ours, except for the fact that here the Cold War never ended and the Soviet Union still exists. To safeguard the balance of world was created a nongovernmental organization, Mithril, made up of mercenaries who do not sympathize or to the east nor the west can be defined as champions of freedom and justice.
Among the most talented members of the organization is Sousuke Sagara, a boy of sixteen who since childhood has known only battlefields, especially in the Middle East, and therefore knows thinking only in militaristic terms. The boy is charged with protecting Kaname Chidori, a normal (and beautiful) Japanese high school student who unknowingly actually hides a big secret. Kaname is a fact, Whispered, and his brain is guarded the secret of Black Technology, a technology so advanced as to render obsolete even nuclear weapons.
Sousuke then must protect the girl, enrolling in the same school, and eventually combined disasters of disasters (see Full Metal Panic? Fumoffu) being used to the fact only the military world, the boy is incapable of understanding the world of civilians, exchanging gestures common to all the other threats and unlikely to lead to coming to school every kind of weapon. The plot then alternates between reckless actions, struggles against terrorists and problems of daily life because of Sousuke become big problems.