Incomplete Sisters

"Sister, we are each other's one and only 'sister', right?" Ryu So-hee is a high school student who dealt with severe illness during her childhood but has now recovered and is leading a regular life. She has a younger sister named Ryu Ah-young, who is presently unwell. Although Ah-young is very attached to her older sister and often follows her, So-hee starts to feel increasingly overwhelmed by her presence. Following a particular incident, a divide opens up between them, and the sisters begin to experience significant discomfort in each other's company. This is a harsh mystery thriller centered on two sisters, set against the backdrop of a dark, concealed family secret!