I feel like growing up, Atsuhiro was always instilled with the belief that he had to remain on the sidelines and its not his place to be in the main spotlight, considering how secretive his familys line of work is, so his dramatic personality and flashy get-up is just something he uses to self aggrandize and mask his inferiority, despite knowing deep down that heβll always remain an unimportant side character. I also think that being born into an elite line of villains, his parents were probably harsh with his upbringing. During final performance, he fulfilled his duty as a support role, being able to feel like heβs actually achieved something great for once. So despite how rushed his character arc is, I feel like his ending was a good closure for his character in a way, had they branched out his backstory more.