Over the course of his career, Osamu Tezuka reused the same characters in different roles in different stories. The way that Tezuka used the characters in his "star system" can be seen as somewhat analogous to a film director frequently casting members of a regular "stable" of actors in different roles. For instance, the "actor" Shunsaku Ban or Shunsuke Ban, who played the detective in Osamu Tezuka's Metropolis, as well as played Astro Boy's teacher in Astro Boy. Tezuka jokingly made a list of how much they were paid and based them on famous western actors in his time.