Arpegius is one of the four main protagonists in the anime film 'Interstella 5555: The 5tory of the 5ecret 5tar 5ystem.' He is the guitarist of the alien band Crescendolls. Arpegius is known for his calm demeanor and musical skill, contributing to the band's iconic sound. Throughout the film, he plays a crucial role in escaping from the antagonist and helping his friends return to their home planet, embodying courage and teamwork during their interstellar adventure.