Dyogrammaton
English name: Dyogrammaton
Genres: Hentai
Type: OVA, Episodes: 2
Aired: Dec 15, 2006 to Feb 23, 2007
Studio: Azeta Pictures
Source: Visual novel
Rating: Rx - Hentai
Synopsis:
Based on an adult game by CLOCKUP 

An enormous monster appears and attacks the city, only to be thwarted by the amazingly voluptuous superheroines! Explosive action, dynamite sex scenes and battle royales take place in this futuristic flight of fantastic proportions that will make you cream in your pants!

(Source: AniDB)