Tenshi no Keisei: 16-nengo ni Mezameta Watashi

Overview

Umi, who had been in an accident in her second year of high school, awoke from a deep sleep for the first time in 16 years. There she finds her parents a little older than she remembered them, and a younger sister who is the same age as she was before she fell asleep. She is welcomed into a strange house with no recollection of her past, and soon realizes that her parents are trying to hide the truth about the accident from her. Why? As she tries to recover her faint memories, fragments of her past gradually come back to her... The past and the present come together in this shocking suspense between the two sisters!

Source: AniList