Beni shōga
Beni shōga (紅生姜) is a type of tsukemono (Japanese pickle). It is made from ginger cut into thin strips, colored red, and pickled in umezu (梅酢), the pickling solution used to make umeboshi; the red color is derived from red perilla. It is served with very many Japanese dishes, including gyūdon, okonomiyaki, and yakisoba.
Beni shōga is not the pickled ginger served with sushi, which is called gari.