Kirara, a modern-day Japanese high school girl known as a "gal," finds herself suddenly reincarnated as Chelsea, a "failed noblewoman" in a fantasy world. Unfamiliar with the conventions of noble society and the typical tropes of reincarnation, she is further trapped by the manipulations of her sister, Jennifer, leaving her with no allies and in an utterly hopeless situation. Despite the odds, Kirara—now Chelsea—decides to take action to change her fate. She seeks out lessons from a strict and renowned tutor and, using her inherent determination, excels in her studies. As a result, Chelsea's social reputation in noble society begins to soar. She also becomes closer to the crown prince, Valentino, and those around him...!?