48x61 is a short film directed by the renowned Rintaro (known for Astro Boy, Metropolis, etc.) for Japanese manga artist and director Katsuhiro Otomo (known for Akira, Mushishi, etc.). The production was handled by Studio Madhouse. The film was created when Rintaro was 61 years old and Katsuhiro was 48, which explains the title. The main characters are Rintarou and Katsuhiro. The plot centers on a bicycle race between the two of them.