tough question huh? yea`. everyone LOVES this anime. maybe it`s beacause it can really relate this to your life or maybe, you just love this cause you LOVE anime. yea that`s it. && the candidate`s for the bishounen' of seiso institute are..
Lili
The fairy that lives on the campus of Seisou and is the one who gives Kahoko the magical violin. Lili is the same fairy that promised the creator of the Academy that he will bless the school with music. He flies around the school waiting for people to notice him, and if they respond, he blesses them with a "magical" musical talent or whim.
Len Tsukimori
A surly, blue-haired, violin player who normally behaves contemptuously toward everyone. He was a child prodigy, coming from a family of musicians. His mother, Misa Hamai, is a very famous pianist and his father is a well-known violinist. Because of this, many people take his brilliance for granted. He seems very cold towards those that he comes into contact with, even his admirers, to whom he rarely pays attention to.
Before he met Hino he didn't think that music was enjoyable, though after spending time with her, he began to slowly enjoy music and his music changes because of her. He slowly warms up towards Hino and even gives her advice on how to hold and stand properly with the violin. People think that he acts harshly towards Hino, but deep down in his heart he is really concerned about her (though he may not show it). As the series progresses, he realizes his feelings for her. He's slowly affected by Hino and his mother says that he has changed his character. His mother knows that Hino is the one that affected him or changed his personality.
Ryoutarou Tsuchiura
Another second year General Education department student, and Hino's friend. He and Kahoko met after he ran into her, nearly knocking her down a staircase, saving her in the nick of time. Their friendship eventually grows, and she even confesses she knew nothing of violin playing. He is a very gifted pianist but quit playing in public because of an unpleasant experience at a junior concert. Ryotaro is the star of the soccer team, being very skilled at the sport (and even outdoing some third years). After he helped Kahoko in the first round of the concours by being her accompanist, he, as well, joined the concours. He does not like Len Tsukimori, and they often get into many disagreements. His feelings for Hino gradually deepens as the series progresses.
Kazuki Hihara 
Hihara is an energetic third year at Seisou who plays the trumpet. He is tall and in shape (he runs every morning), and has green hair and eyes. He's aggressively friendly and outgoing and has little sense of social boundary. Hihara has an enormous appetite, as he is constantly eating (especially baked goods). He quickly befriends Kahoko. In the middle of the series, he starts to call Kahoko "Kaho-chan", instead of the usual "Hino-chan", this suggesting he has a rather obvious crush on the girl. He also admits to Azuma that he has a crush on Kahoko, saying "don't make fun of me" when asked. Basketball is one of his favorite sports.
Azuma Yunoki
A student in his third year, he appears to be a very considerate and kind, this helps to hide a meaner and more intimidating man. He is tall and smart, his hair a deep purple and longer than that of the female characters. He comes from a family of flower arranging. He also used to play the piano, but due to the law that the youngest son cannot be better that his brothers, he turned to the flute. The charming and considerate flautist "prince" of the harem, he has a worshipful trio of fans that hate any girl he shows any attention to, Kahoko in particular. He has strong feelings for Kahoko, but acts like he really hates her.
Keiichi Shimizu
A blond 'bishounen' and also is the youngest male competitor, he plays the cello. He is very drowsy all the time and often seems confused. Shimizu can be found sleeping anywhere, anytime, so Kahoko first meets him lying on the ground fast asleep. His life seems to revolve around music (he tells Hino that he sleeps, wakes up, plays the cello, then repeats the process, other than eating and visiting the library), and he loves to play his instrument. He enjoys reading and studying music history and structures of instruments. In time, he becomes interested in Hino because of her carefree music.
Hiroto Kanazawa
The lazy music teacher with greyish-lavender hair who is the head of the competition. He is always seen smoking, and sometimes when outdoors he is seen feeding his cat. He seems to know about Lili, but claims that he cannot see him. In the anime, his talent is singing.
Shinobu Osaki
He is a Seisou graduate, with reddish-orange hair and who is also in his 3rd year in a university currently and as a support teacher for the orchestral club. In the past when he was still in high school, he won first place in the competition. His reason for playing the violin is to make listeners happy. He has a gentle heart, and he was the one who cheered up Kahoko after she started questioning her abilities of relying on the magical violin compared to the music department's students hard work in episode 12. He also enjoys teaching young children to play the violin, and has even gotten some of the concour participants to help him with it.