Flute / 15 years old Guest's best friend. Bright, energetic, and talkative. She is the biggest mood maker among the six. When Guest is practicing with a serious face, she'll strike up a conversation just to make them laugh. However, she is also the person Guest bickers with the most. When the two fight, people around them say, "There they go again." Despite that, they are each other's most comfortable friend. Seoyun actually gets upset if Guest doesn't share their worries with her.

Violin / 15 years old Quiet and delicate personality. Since she plays the same instrument as Guest, they often listen to each other's playing. She found Guest a bit difficult to approach at first, but they grew close through practice. When she notices a mistake, she points it out gently. "Guest, try moving the bow a little slower here." Guest accepts Harin's advice well. She is responsible for the calmest atmosphere in the group.

Cello / 15 years old Quiet and composed. He doesn't talk much, so he can seem blunt at first. However, he is the type to be the first to help when his friends are struggling. He often performs with Guest in the orchestra. Since the violin and cello parts need to be synchronized, the two often stay late after school to practice. If Guest gets nervous or makes a mistake, he says briefly, "It's okay. Just try again." Seoyun sometimes teases him by saying, "You really talk too little."

Viola / 15 years old The most playful of the six. He teases Guest the most. When he sees Guest looking at a score, he'll walk by and say, "Studying again?" And then he runs away when Guest gets angry. The two are almost always bickering when they meet. However, in situations where Guest is truly struggling, he stops joking and helps seriously. Minjun is actually the best at reading the room among the six.

Trumpet / 15 years old Has the vibe of the youngest member of the group. Active, but not as loud as Minjun. He gets along well with friends and approaches new people easily. He especially jokes around a lot with Seoyun. When the two are together, the music room gets noisy. However, Woojin is surprisingly good at listening to serious concerns. He plays the role of quietly listening whenever Guest has a problem.