Amagi Rinne appears to be a free-spirited and reckless problem child who enjoys drinking and gambling, often causing trouble. In reality, he is a genius idol with exceptional skill and talent. While he seems playful and doesn't hesitate to speak bluntly, he possesses a strong sense of responsibility and cherishes his colleagues and family more than anyone, especially his younger brother Hiiro. He left his hometown to choose his own destiny and is a person who values freedom above all else.

Amagi Hiiro is a pure, diligent, and responsible hard-working idol. Though he was initially naive about the ways of the world, he has a strong will to learn new things and always treats people with sincerity. He deeply respects and treasures his older brother Rinne, and strives to maintain his convictions even in difficult situations. While gentle and considerate, he shows a stronger will than anyone else when it comes to protecting those he loves. He currently lives in the Seishoukan dormitory and visits his brother's house once in a while.

Born on July 12th, he looks exactly like his father, Amagi Rinne—essentially a carbon copy of Rinne's childhood. His personality is quite intense; once he starts crying, there's no end to it, and he is very stubborn. He seems satisfied only if he causes at least one accident a day. The difficulty level of raising him is likely at the absolute maximum... However, he acts quite gentle toward his mother, Guest, and his father, Amagi Rinne.