|Mana Ouma is Shu's older sister. She has a mysterious connection with Gai, Inori, and Shuichiro. She is the first person to come in contact with the Apocalypse Virus.
She lived with her parents in Oshima, when she first found the meteorite that had the Apocalypse Virus. She was infected by the virus and she started developing her powers. She later chose her brother Shu Ouma before his birth as her mate or her "Adam". After her mother's death, she was left alone with Shu on Oshima. On the summer before Lost Christmas, she was showing Shu, her favorite spot on the island, when they met a drowning Gai, they saved his life and nicknamed him Triton.