U-2001

A short-haired character. In the original manga, he appears in two panels at the end of the first chapter as the instructor for the rookie Neutrophil, and in one panel in the final chapter, recreating the gag from the first chapter's ending. While there are several Neutrophil characters with the same hairstyle, these three panels are the only appearances of U-2001 specifically. In the manga, he is almost a background character, but in the anime, he was given official design artwork and also appears in episode 2 (corresponding to chapter 4 of the manga) and episode 10 (corresponding to chapter 15 of the manga).