TV-Series
Description
Haruto Mizushima is a first-year student at Seiso Academy, where he belongs to the music department and is an active member of the orchestra club, playing the cello. He is a young teenager with light blond or yellow hair and yellow eyes, and his height is 162 centimeters. He is the cousin of fellow musician Arata Mizushima and a childhood friend of Sousuke Nanami, having learned to play the cello alongside him.

Haruto possesses a strict, straightforward, and serious personality, holding himself and others to very high standards. He dislikes dishonesty and has a strong aversion to people he perceives as slacking off or possessing weak, "half-assed" motivations. Despite his blunt and sometimes quick-tempered nature, he is fundamentally honest and fair-minded, willing to apologize when he has made a mistake or judged someone too harshly. He is a dedicated and hardworking individual, often locking himself in practice rooms to focus on his music, and this diligence extends to his home life, where he helps his grandfather at a shrine, making him well-loved by the local people who visit. His home is a shrine located in the Motomachi district, where he lives in a large family household that includes his grandparents, parents, aunts, and even pets such as cats and chickens.

Within the story, Haruto is a key member of the orchestra ensemble assembled for a national competition. His primary motivation stems from a deep respect for the art of music and a belief in the importance of dedication and team solidarity. He values harmony and a natural flow in the group's performance, believing that results without effort are meaningless. This conscientiousness initially causes him to clash with fellow member Kyoya Kisaragi, whose indifferent and emotionally whimsical attitude Haruto finds offensive and irresponsible. Similarly, he was initially opposed to the inclusion of Kanade Kohinata and Kyoya Kisaragi in the ensemble, questioning their skills and lack of apparent enthusiasm, and insisted on an audition to fairly assess their abilities. However, consistent with his fair nature, after witnessing their talent, he not only accepted them but also apologized for his earlier narrow-mindedness.

His key relationships are defined by his sense of fairness and dedication. He is seen as a reliable and mature team player, often acting as a voice of reason within the group, and he gets along well with Ritsu Kisaragi, the vice-president of the orchestra, whom he respects and follows for his own seriousness. His childhood bond with Sousuke Nanami is significant; he knows the extent of Sousuke's talent and was angered when Sousuke was rejected from another school's ensemble, believing it was an unfair judgment. Despite his blunt demeanor, he is protective of Kanade, viewing it as his duty to shield her from his cousin Arata's easygoing and flirtatious nature.

Throughout the narrative, Haruto shows clear development from a rigid and judgmental individual to a more accepting and collaborative one. While he remains strict, he learns to trust and embrace his teammates, moving past his initial harsh judgment of Kanade and Kyoya to become a supportive colleague. In one instance, after a minor accident involving his grandfather that he felt responsible for, he locked himself in a room to reflect, demonstrating his serious and self-critical nature.

Notably, he is often called by the nickname Haru by his ensemble members and close acquaintances. His notable abilities extend beyond music; he holds a second-degree black belt in kendo, a hobby that speaks to his disciplined character. He also possesses a remarkable memory, capable of perfectly memorizing an entire page from a dense theoretical textbook. His own cello playing is described as calm and stoic, yet subtly emotive, reflecting the fairness and harmony of his personality, which allows him to unite with and mesh well with other playing styles.