Cross Helix

SDI, a giant global complex, builds a leisure facility for adults with a casino and deploys "dolls" that provide sexual services. At the same time the United Nations start a crackdown on prostitution. A human brain is found in the discarded doll. SDI denies any association and suggests to place a UN branch office in the playtown.
Several years later. Main character visits playtown as a UN moral administrator and gets involved in huge conspiracy over braindolls...

[From vndbreview]