She lives with her mother and older sister as well as having an older brother studying in a university but it is unknown whether or not her father has been mentioned in the story. She confesses to have a strong craving for sweet things.
Kahoko has never played or touched a violin until she meets the strange music fairy, Lili. Though at first reluctant about playing the violin, she soon begins to love music. She is a polite and considerate girl who puts others' feelings before her own, though at times she can appear rather naive, especially in music. The boys involved in the concours have obvious crushes on her, though Kahoko is unable to figure that out.
In the TV special Secondo Passo, she took up a part-time job working in a music shop to finance her violin lessons. She was also excluded by the academy's director Akihiko Kira to form an ensemble to take part in a grand festival. She was upset by the director's decision. Aoi Kaji then took her out on a date to cheer her up. He then reveals the reason he transferred here.
In the more recent chapters of the manga, she is shown more frequently and felt sad upon knowing Tsukimori will leave to study abroad.
His mother is a piano teacher, revealed through Minami's conversation with Kahoko in the anime. He also has a younger brother and is good at cooking.
He is a very gifted pianist but quit playing in public because of an unpleasant experience at a competition because of the judges' discrimination of younger contestants. After he assisted Kahoko in the first round of the concours by being her accompanist, he, as well, joined the concours.
In the past, he had a girlfriend called Mizue Sakamoto, and in episode 14, they met again by accident at the train station with Kahoko and Len where she mistook Kahoko as Tsuchiura's girlfriend at first, then Len's girlfriend after.
Tsuchiura is the star of the soccer team; he is the team midfielder. He is very skilled at the sport and even outdoing some third year students. Even so, Mizue said that he was skilled in both basketball and soccer, which Mizue points out that whenever he plays, there will always be girls cheering for him. As told by Mizue, he was also in the basketball club when they were in middle school.
He does not like Tsukimori, and they often get into many disagreements. Their arguments can vary in topics, from a notebook to their style of performance.
His feelings for Hino gradually deepen as the series progresses and going as far as secretly calling her Kaho during the quintet's performance.
In Chapter 37 of the manga, he admits to his ex-girlfriend, Mizue, that indeed, he likes someone - that someone being Hino, to whom he is thankful because she was the one who had helped him rediscover his love for the piano.
Later on in Chapter 55, in an attempt to make Tsukimori realize his own feelings for Hino, Tsuchiura confesses, "I ...like Hino." In Chapter 65, he gets angry at Tsukimori for "not doing anything about it", referring to Tsukimori's feelings towards Hino. In chapter 71, he told Kahoko "I like you."
In all of the game series, he was able to sense and see Lili, The fata. Alongside with the other Concour's Particpant.
He explained to Kahoko that one day he went to the rooftop to have lunch, however when he arrived, there was a female senior playing the trumpet. He was amazed at how she played. Soon after, she was there every time he went to the place to have his lunch. Later, she brought a trumpet she borrowed from the school's music room. This finally allowed him to have a try on playing the trumpet. Nevertheless, at that time, he already joined the school's track team and he was reluctant to leave and join the school band. However, in the end he had his friend's support and quit the track team.
Kazuki has an enormous appetite, as he is constantly eating. He quickly befriends Kahoko. Because of him, Kahoko learned the true meaning of music, that it is enjoyed by everyone. After that Kahoko began to love and enjoy music better. In the middle of the series, he starts to call Kahoko "Kaho-chan", instead of the usual "Hino-chan", thus suggesting he has a rather obvious crush on her. He is the first one to realize he likes her, and becomes overly conscious of her afterward.
He's a member of the Orchestra Club.
He has an elder brother named Haruki.
In Kiniro no Corda 3 he is 25 years old and is helping out the orchestra club, the role Shinobu Ousaki once filled in.
He is a violin virtuoso. Born in a family of musicians, Len felt overshadowed by his parents' music and strives for perfection in his music. He holds a high standard and demands the best from himself and from others. Len's father is a well-known violinist and his mother is a famous pianist called Misa Hamai. He is fluent in both English and German. In one of the chapters, it has been shown that Len knows how to play the piano.
Len didn't believe that music was enjoyable, though after spending some time with Kahoko, he slowly began to enjoy music. With this, his music changed and even his mother has noticed the change that was influenced by Kahoko.
Others may think that he acts harshly towards her, but deep down in his heart, he is concerned about her although he does not show it. As the series progresses, he realizes his feelings of love for Kahoko. It becomes more obvious in the more recent chapters of the manga; for instance, while everyone else knows that he is leaving to study in Europe, he finds it the hardest to tell this to Kahoko, and he doesn't really understand why. Instead, he claims that his leaving has nothing to do with her.
It takes Ryōtaro, who tells Len that he (Ryōtaro) likes Kahoko, to make him open his heart and acknowledge certain things regarding her. It's also seen that it is only around her that he blushes furiously later on in the series - for instance, when she held his hands, and when he walked her home. In chapter 63 of the manga, he becomes fully aware of his feelings when he thinks "My feelings for you...if it is expressed in words, then it is Love."
In chapter 63, (titled : Ave Maria) Len finally realizes his true feelings for Kahoko. It seems that his feelings were confusing for him for a long time, but then he realizes that he loves her. In chapter 65, Len was encouraged by Kahoko to go see Tsuchiura's performance. Before the concert, Len was depicted to only stare at Kahoko during that time. Yunoki told him that was too obvious.
Yunoki also found out Tsukimori has feelings for Hino. The time Tsukimori didn't want to tell Hino that he was going to leave in a week, Tsuchiura was so angry because Len was being cruel to Hino. Len told him that even though he confessed to her, it would not change her performance during the contest.
In Chapter 67, he hugs Kahoko and tells her that he will be leaving for his trip the next day, which happened to be the day of her performance. In Chapter 69, as Tsukimori was about to leave for his trip, Tsuchiura looked for to convince him to watch Hino's performance. Tsukimori then buys flowers for Hino, but does not stay to the end to see her after her performance, instead asking Tsuchiura to pass the flowers onto her. When asked why, he tells Tsuchiura that 'that performance was more than enough.' After finding out Tsukimori had been and had already left, Hino runs out of the hall to find Tsukimori. After seeing her on the side of the street just after getting into his taxi, he gets out and tells her that he heard her performance and how much he enjoyed it. After giving Hino his coat due to her lack of warm clothing and hearing her promise to work hard at the violin, he departs and is currently studying in Vienna.
Chapter 74 from the manga marks Len's return to Japan, and a confrontation between him and Kahoko ensues.
The manga closes with Chapter 75, where Len indirectly confesses to Kahoko about his feelings. Lili appears once again, and sees the two together(hugging) and brings kahoko the music of happiness.
In Kiniro no Corda game, he can see Lili, the Fata.