According to a manga by Asagiri Yuu.

The traveling musical group The Pussycats may be the hottest thing around. Lou, Kei and Sonya are three, sexy singers having a legion of screaming fans in every town. But these pussycats have claws.

Singers by day, assassins by night. Unbeknownst with their fans, The Pussy Cats are the Midnight Panthers - female assassins who'll kill anyone if the price is right! Their next target is a despotic king who rules by fear and crushes dissension with the iron fist. Nevertheless for one of the Panthers, it's not only another job... it's personal.