The color choices weren't just random. Since the gimmick of the shirt is revealing his mouth, his look corresponds with the uniform color he had at the time. His hair from the movie zero corresponds with the light blue color he had covering his face as a second year and his in-season hair matches with the darker blue T like the uniform he has as a third year. The kanji on the light blue reads “Tsubureru or Get crushed”, like how he yells it in the movie. This is also why his mouth is open to show his cursed speech markings. The kanji on the dark blue shirt reads “Okaka or Bonito Flakes”, one of Inumaki's safe words, and because it is one of his safe words, he is seen smiling.