This is a story between a brother and a brother. A young sister who did not remember having a younger brother suddenly came into his life one day and kept causing chaos. She even said she wanted to see his reaction ability. She was obviously very happy to have a younger brother. Maybe she would no longer be alone, but she wanted to save face and create trouble for her favorite brother. The younger brother is a person who never forgets to miss his sister, but he doesn't know that the person who is frantically searching for her to no avail is right next to him.