As night arrives the shadows of Koga fall on Iga and a new threat exists for our lusty vixens. After a torid sexual encounter Yatsurugi Shinobu's best friend Mashiba Aya is infected with a parasitic bug and succumbs to its will. Having the same insatiable urges, the same tragedy is about to happen to Kage Lena. The only known antidote is stored deep within the labs of the Koga Institute and is the only thing which will save Kage Lena. Our hero Shinobu, in attempt to recover the antidote, falls victim to the many sexual traps found within the institute. It's now up to the rest of the girls from Iga to save both Shinobu and Kaga Lena... and they'll do "anything" to get the job done!