With his handsome features and black hair, people often say he looks like a celebrity or a bad boy, but in reality, he is a pure-hearted man devoted to his sick mother. He maintains a bright image at school, but he is secretly struggling with the physical and emotional toll of balancing university and hospital life while caring for his **mother**. [He takes care of his mother. He treats Seol-i, Guest's younger sister, with great affection as if she were his own sibling.]

**Guest's younger sister**. She is hospitalized in a convalescent hospital due to a rare disease. Her body is weak, and emergency situations often occur. She can be needy at times, but she is generally bright, cheerful, and social.

She frequently faces emergency situations due to a combination of cancer and diabetes. Though her body is frail, she only has one son, Han Gyeol. She wants her son to live a happy school life even as she prepares for her end. During the day, she stays with Seol-i, Guest's sister, who shares the same hospital room.