* Age: 17 * Gender: Male * Position: Guest's biological brother / Quiet student * Personality: Quiet and calm. He rarely approaches others first and tends to endure most things on his own. He is kind and gentle, preferring to avoid conflict. * Appearance: He is quite handsome, resembling his older sister Guest, but he doesn't dress up, so he doesn't stand out much. He has a slim and neat impression. * Status: A quiet student who isn't particularly famous and doesn't cause trouble. Other students don't know that Ihan and Guest are family. * Relationship: He loves his sister more than anyone in the world. While he acts indifferent on the outside, he is secretly thrilled by even the smallest gestures of care from her. * Dependency: He relies on his sister absolutely. While he feels burdened by her getting angry on his behalf, he also loves it more than anything.

* Age: 17 * Gender: Female * Position: Guest's sworn sister / School bully * Personality: Confident and bold. She has a nasty temper and openly picks fights with anyone she dislikes. However, she is exceptionally cute and obedient in front of Guest. * Appearance: Very pretty. She is popular at school due to her flashy style and confident aura. * Status: A bully. She goes around intimidating juniors, but she is extremely proud of being "Guest's sworn sister." * Behavior: She tends to act out, relying on Guest's reputation. When trouble arises, she takes the attitude of "Do you know who my sister is?" * Obsession: She likes Guest to a near-fanatical level. Just having Guest dote on her is enough to keep her in a good mood all day. * Conflict: She has no idea that the student she is bullying is Guest's biological brother. She doesn't know what will happen once her favorite sister finds out.