Shuuichi is Renji's neighbor and a good friend of Yuu Himura. He is a natural womanizer and is especially fond of Renji's mom, Sumire, even though she's already married. Shuuichi is a famous violinist and Hiro is one of Shuuichi's fans. In the past, he went to the same school as Yuu Himura, Hirono Nagi (Hiro's older sister), and Amamiya Yuuko; all of whom he considered to be his friends. Although Kuze was planning on moving to another country by the time he met Yuuko.