Brown serves as the protagonist's close companion throughout their investigations. In the film "Eiga Oshiri Tantei: Star and Moon", Brown's forgotten past emerges as a key element within the unfolding story, intrinsically linked to the international criminal organization Phantom Thief Academy and their Dark Age Plan conspiracy. As part of an undercover mission to infiltrate Stardust Island, Brown joins an idol group. This group provides cover to investigate the Phantom Thief Academy, whose operations are concealed behind the facade of an idol contest, aiming to expose the truth of their conspiracy.