Umi no Yami, Tsuki no Kage  

Dark Sea, Moon Shadow, Darkness of the Sea, Shadow of the Moon, Морская Тьма, Лунная Тень, 海の闇, 月の影, Darkness of the Sea, Shadow of the Moon, Umi-Yami

The story revolves around two sisters named ruka and rumi who are both in love with the same man, katsuyuki touma. initially, rumi is supportive of ruka's relationship with katsuyuki. however, things take a turn when the twins become infected with a bacterium that changes rumis personality and grants them psychic powers. now, driven by her desire for katsuyuki, rumi will do whatever it takes to get in between him and ruka, even if it means going against her own sister.