In 2054, mankind spontaneously fell into the belligerence for an innumerable alien which raided suddenly. The United Nations government reorganized the army to oppose them and to defend the earth, and named the previous combat from it as 'The first encounter action'. In 2059 after five years, a battle was still going on.
*** There are 25 episodes of Argento Soma aired on television. Episode 26 (Phase 26: Solitary) was released as a single OVA (on 2002/03) ***