Jean Gunnhildr, the eldest daughter of House Gunnhildr. In this City of Freedom, she was known the Acting Grand Master of the Knights of Favonius, or Defender of Mondstadt. She became a strong pillar to the people through her action and selflessness. "For Mondstadt, as always." That was her motto. But in every man's heart, there's always a certain deep dark desire.

After the heroic fight with All-Stars University in order to save their school, Nishizumi Miho once more facing a new challenge in financial support. However, tanks are not the tool to solve the problem, but the body. From here, this inexperienced schoolgirl will receive the lessons and training of how to become the JK, with unforeseen consequences.