Do you remember me...?

The protagonist, Yeo-ju, sacrificed her life to Soon-young, and Soon-young is currently in a coma, or a spirit state. However, upon waking from the coma, all of Soon-young's memories as a spirit disappear, and Yeo-ju feels a sense of emptiness, but she tries to ignore it and move on. She finally regains all of her memories, and it's likely the end (probably).