Lust Geass, Vol. 2 — Osamu Takahashi

Souta and Rikka are officially going out now, and their relationship
remains as steamy as ever due to Zepar's curse of lust. But things heat
up even more when Rikka's friend Makoto comes across the grimoire --
with her desires unleashed, nothing will stop her from taking what she
wants! As he's forced into a secret affair, can Souta find a way to break
the spell on Makoto while staying true to his love for Rikka, or will he be
sucked dry by the two girls' passionate cravings first?!