Rei Zero
Japanese title: レイZERO
Type: OVA
Source: Visual novel
Episodes: 2
Status: Finished Airing
Aired: Jun 26, 2010 to Apr 1, 2011
Duration: 27 min per ep
Rating: Rx - Hentai
Studios: Anime Antenna Iinkai
Producers: Pixy
Genres: Hentai

Tokyo fell into ruins following the consecutive great earthquakes of 2014. As a result, the new city center is built in the location of the former Nishitokyo. Meanwhile, Shinjuku and the submerged Minato wards devolved into slum areas. Further, due to the Immigration Laws of 2040, these slums saw an influx of refugees, mafioso, and terrorists, and is now the leading crime capital of the world. 

The year is now 2049, and this is the stage in which two women embark on an operation to arrest a dangerous drug dealer. 

(Source: translated and adapted from official site by Cranston)