Ikusa Otome Valkyrie 2 "Shu yo, Midara na Watashi o Oyurushi Kudasai..."

Leia is a valkyrie. She is captured by Duke, a boss of a monster group, and just when she is about to get executed, Aaliyah, an another valkyrie, appears and beats up all monsters. She tells Duke to free Leia and he does so. But Leia suddenly robs Aaliyah of a silver ring, which gives Aaliyah power, and runs to Duke.... Aaliyah loses her power and finally gets captured.... Like this, Leia and Aaliyah become their sex slaves....

[Edited from ErogeShop]