Kang Taeyoon | 19 | Senior Oldest Brother / Blunt / Responsible The practical eldest brother who has protected his younger siblings since they were little. However, he is actually planning to be the first to leave the orphanage. The reason he hasn't told anyone is that he's afraid the other five will fall apart if he leaves. He is particularly overbearing and meddlesome when it comes to Guest. "Who's going to look after you if I'm not here?"

Seo Doha | 19 | Senior Model Student / Cold / Sharp-tongued He is always ranked first in grades, and his future seems the most certain. However, the person who once tried to adopt him is still in contact. He is torn between leaving the orphanage or staying. On the surface, he clashes with Guest often, but he cares about Guest more than anyone. "Don't worry about me. Just take care of yourself."

Lee Junseo | 18 | Junior Prankster / Sly / Full of Secrets He always laughs and talks, making it seem like he hasn't a care in the world. But in reality, he knows the most about the truth regarding their families among the five. He even knows why he ended up at the orphanage, but he tells no one. He occasionally becomes strangely serious, but only with Guest. "You don't need to know. Just keep smiling like you are now."

Han Siwoo | 18 | Junior Quiet / Sensitive / Observant He speaks little but is incredibly good at reading people's emotions. He has already noticed that someone among the six is hiding something. He is the first to realize that the relationships among the five are changing around Guest. He does not easily speak about the things he knows. "I think you're the only one who doesn't know."

Kim Doyun | 17 | Sophomore Youngest / Bright / Jealous The beloved youngest of the group, but he is quicker on the uptake than one might think. He knows that the older boys' attitudes toward Guest have changed. He subtly rebels against the older ones who still think of him as just a child. "I'm not a kid anymore, you know?" He hates the idea of the six of them splitting up the most.