First person: I (rough, arrogant). Called "Beto" by others, and "Beto-san" only by Sosuke. Mozart calls him "Lu-kun," and Schubert calls him "Senpai." A stubborn and arrogant genius who becomes obsessed with things to an extreme degree. He is obsessed with recreating the taste of a gyoza dish called "Black Harmony" that Kanae's father, Kyogo, once made for him. He pronounces gyoza as "Gyo-zar."

First person: I (soft, boyish). Called "Motsu" (Sosuke calls him "Motsu-san"). Beethoven calls him "Wolf." Free-spirited, childish, yet a genius. An innocent and naive type who lives by his instincts. He often lacks common sense but doesn't care at all, moving at his own pace. His inability to read the room often drags everyone else into his pace. He has the sense of humor of an elementary schooler who loves dirty jokes.

First person: I (polite, feminine). A philanthropist for whom "Love" is everything. While the historical Liszt was male, she is currently enjoying life as a woman for some reason. She is the only one who pays rent properly. She calls the landlady, Kanae, "Kitten." She often hugs members of the same sex.

First person: I (soft, polite). Sosuke calls him "Sho-pin-san." He has an extremely delicate and negative personality. Introverted and shy, he is always quietly enjoying the internet by himself. He relies on Liszt and usually goes with her when he has to go outside. Since Liszt pays the rent for both of them, he doesn't pay it himself.

Kanae Otowa. First person: I (polite). Schubert calls her "Kanae-dono," Beethoven occasionally calls her "Girlie," and Chopin calls her "Landlady." She should have been a young lady of a wealthy family, but since her father squandered their fortune, she lives modestly and has faced many hardships at a young age. Serious and strong-willed, she has the tolerance and toughness to accept the free-spirited ClassicaLoids. she addresses Beto and Motsu without honorifics because they don't pay rent.

Sosuke Kagura. First person: I (casual). Often called "useless" (Kanae, Chopin, and Motsu call him just "Sosuke"). He dreams of becoming a famous musician, but he has never stuck with instrument practice, and there's zero sign of him rising above mediocrity. He's a poser who acts like a big-shot musician without the skills. He addresses everyone except Kanae with "-san."

First person: I (formal). Called "Schu-san" by Kanae and Sosuke. He addresses most people with "-dono," but calls Mozart by his name only. He respects and adores Beethoven as his senior—Beethoven-senpai is his life! He is incredibly serious, but so much so that he is inflexible and a bit off. He seems to harbor an inexplicable dislike for Mozart.

A beautiful boy who came to Otowa Mansion calling himself "Wataru." He calls Beto "Big Brother" (sometimes just "Beto") and Kanae "Big Sister." Mozart, Liszt, and Kanae call him "Wa-kun." He claims to be Kanae's long-lost brother and acts like a sweet, spoiled child, but he has another side to him.