Instrument: Viola (previously Violin)
Birthday: November 12
Blood Type: AB
Hair Color: Blonde
Eye Color: Emerald green
Kaji is one of the new characters who appears in the second game and was introduced later in the Chapter 47 of the manga. He's a new student in the General Education department, who transfers to Seisou and is sorted into Kahoko's class. He previously played the violin but dropped it and now plays the viola because of an incident in the past. He first met Kahoko on the local park when he overhears her playing the violin and he was so captivated by it that he openly declares himself her number one fan. He admits that he doesn’t have confidence in his own performances since he lacked training, but he has very sharp hearing and can easily spot flaws in others’ performances. He is also very fast in tuning his instruments. He addresses everyone politely, as he (like Azuma) was also brought up in a respectable and wealthy family. Aoi, however, was allowed more freedom by his family. He doesn’t get along with Azuma, often exchanging cynical remarks with the upperclassman, and he is perhaps the only one other than Kahoko to know Azuma’s true personality.
His grandfather owns a hospital and his father is a politician. His grandfather hopes that Aoi will major in medicine, so that Aoi will someday take over the position as head of the hospital. Aoi is extremely smart and athletic, though has a rebellious streak of his own.