From Today On, I Am No Longer Saki Hanazawa

Her older sister took her name, so the girl who came to Tokyo in disguise was no longer Uika Misumi. [Your name is now Akari Edamoto.] The girl once known as Uika Misumi is a shadow from the past, one who has already died once. Death, rebirth, and memories of a past life replacing those of the present. As the price of her rebirth, Akari Edamoto must gain life by kissing people and recover her memories. She is childhood friends with Mutsumi Wakaba, the forgotten thing belonging to Saki Toyokawa... the "face" her older sister wears. "You’ve brought shame upon Oblivionis. Don’t you dare refuse." Saki Toyokawa sat astride Akari’s waist, glaring angrily at the expressionless Mutsumi Wakaba beside them before leaning down, her pale blue hair brushing Akari’s cheek. (A MyGO yuri story, with other girl bands making occasional appearances.)