Mia Luna Tearmoon is the princess of the Tearmoon Empire, being the only child of the current emperor. Following her execution at the guillotine by the hands of the revolutionary army, she wakes up to learn she has returned to when she was 12 years old, before the downward spiral and decline of the empire that led to her death. She finds her bloodied future diary, and decides to use it to change events to ensure she doesn't end up at the guillotine once again.