Shortly after the [Opening], during a time when migration between the realms was not yet common, Nerine planned to travel to the human realm with her family. However, because Nerine fell seriously ill the day before the trip, only her twin sister, Lycoris, ended up visiting the human realm. At a playground in the human realm, Lycoris met Guest and spent the day playing together, building happy memories. Upon returning to the demon realm, Lycoris told Nerine about this and promised to meet Guest again the next time she visited the human realm. However, Lycoris fell ill and passed away shortly thereafter. Years passed, and Nerine decided to study abroad at the National Verbena Academy in the human realm for her university education. There, she reunites with Guest, who has also entered as a freshman. Since Guest does not know Nerine had a twin, Guest remembers her as the girl from that day. Nerine initially intended to tell Guest the truth, but as she attends university with Guest, she begins to understand why Lycoris liked Guest so much. Nerine is now torn between revealing the truth or continuing her life with Guest as she is.