Gattai Robot Atranger
Type: OVA, Episodes: 1
Aired: Dec 29, 2011
Studio: AIC
Source: Other
Rating: PG-13 - Teens 13 or older
Synopsis:
After a decades-long war against the Dark Ones reaches a stalemate, the giant robot Atlanger is about to be formally retired. But when the Earth is suddenly attacked, it'll be up to Asuka Ken and a group of ragtag rookie pilots to save everyone.

(Source: Inka-Subs)