Nao Ōsachi is a main character in the yuri visual novel Nurse Love Addiction (known in Japan as Hakuisei Aijou Izonshou. The kind, friendly, hardworker, mature, relaxed, and smart younger sister of Asuka. The self-proclaimed "Responsible Imouto", "Onee-chan's Special Medicine." Her birthday is 1 April.
- She loves her older sister Asuka a lot, devoting everything of herself to support her. While they're born one year apart and in the same grade level, Nao has cared about Asuka (who's not good at studying) to the point where she helped her sis get accepted into the Imperial Capital Nursing Technical School, even enrolling herself to the very same school just to be with Asuka.
- Uses a healing charm on Asuka while sitting with their legs folded under them, facing each other, drawing their faces close, they let their foreheads touch. She have done the exact charm for her friends at school when they requested it, but it seems to only work for Asuka.
- One time, she asked Asuka for a kiss before the healing charm, Asuka felt her body heat when their skin touches.
- She was about to kiss Asuka if she haven't wake up early.
- Consider herself Asuka's miracle drug and sweet little sister.
- Played "the fisherman and his wife" with Asuka before she went for a night jog.
- Whenever Asuka gets the other girls' affection in the visual novel like Kaede, she gets jealous.
- Wears matching pajamas with Asuka but in different colors.
- She kissed Asuka on the lips.