Pon'z: The Hunt for S.D.W.

In January 1998 cloning technology produced DNA manipulating virus capable of completely suppressing sexual ability, and it started to be used as a weapon. Three clones with this ability landed in Japan causing nation-wide economic crisis. The government formed a unit to counter this threat and managed to capture one of those three species. After several months of continuous disaster portable machines for capturing SDW were invented and one more SDW species was caught shortly. And now it has become known that the last one is hiding inside a certain high school. Hero is requested to infiltrate the school, identify and neutralize the threat.

[From vndbreview]