Cello, viola, violin, clarinet. That’s all it takes to make people move. Well, that and some skill.
The Broken Quartet is a band that boarded the Jade Moon in Episode 34. They are diagetically somewhat responsible for the soundtrack of Sangfielle.
The Broken Quartet are four fairly ordinary people, shabbily dressed in formal concert wear. They are musicians who once were the finest string quartet in this region (possibly around the Panic), and then something happened. They forgot how to play their instruments, in a mysterious and traumatic fashion, and may have also lost them; but they have pieced some things together, and leaned into the ruin of the thing.
The violinist is the band leader. The band once encountered a mysterious exact double of the violist in a bar in Cantbank, and are unsure which one they took back, as the violist has been acting off lately.