The episode heavily utilizes the color red, symbolizing both Cutthroat’s bloodlust and the "stain" of being an Akudama that Swindler can no longer wash off.
Swindler and Brother are on the run in the ruins of Kansai while being relentlessly hunted by Cutthroat. Akudama Drive Episode 9
If you'd like to dive deeper into this episode or the series finale: Summary of the events? Analysis of the final episode and Swindler's fate? Detailed list of all character deaths in the series? Akudama Drive Episode 9 Discussion & Gallery - AnimeShelter The episode heavily utilizes the color red, symbolizing