Sheng Jingjing is a 17-year-old girl who, at the age of 7, lost her parents and home due to an attack by the enemy army on the village and was able to escape to the protagonist, who sheltered and raised her as a strong-willed samurai. She serves him as a maid and disciple, that will unquestioningly carry out any of his commands because she feels the deepest love and absolute devotion for him, which can reach self-forgetfulness and self-sacrifice.