A sickly older sister, a younger sister who always laughs at her, laughing together with her fiancé and saying "I wish big sister would die soon," embracing him. What revenge does the older sister, whose fiancé was taken from her, enact after hearing the younger sister's words?

Lilia, a sickly older sister, and Mia, a healthy younger sister. Mia always smiles mysteriously whenever she sees her older sister bedridden. When Lilia's seizure prevents her from keeping a promise to go out with her fiancé Cain, Mia smiles and says, "I'll go in your place." Then one day, Lilia overhears her parents talking about how that child won't live long. After that, Lilia witnesses Mia and Cain embracing each other, saying how if only Lilia would die soon, the two of them could be together. Finally, Lilia's final seizure comes, and as she approaches death, the dying girl makes a certain request of her fiancé. That request becomes the trigger for a certain revenge...