Formerly, the Fallen Daughter of the Duke Series by Ichibu Saki, Ushio Shirotori

Claire Martino has a fairy-tale life anyone would envy, with a noble upbringing, a crown prince for a fiancé, and a promising future ahead of her as Noston’s most powerful mage. That is, until everything crashes down around her when all of the family magical talent goes to her half sister, Charlotte, instead. With her engagement broken and reputation tarnished, Claire flees the only life she’s ever known and sets off on an adventure to find the freedom she’s craved all along... moreClaire Martino has a fairy-tale life anyone would envy, with a noble upbringing, a crown prince for a fiancé, and a promising future ahead of her as Noston’s most powerful mage. That is, until everything crashes down around her when all of the family magical talent goes to her half sister, Charlotte, instead. With her engagement broken and reputation tarnished, Claire flees the only life she’s ever known and sets off on an adventure to find the freedom she’s craved all along. It’s anything but easy, but fortunately for a girl with dignity, talent, and a whole lot of bravery, nothing is impossible...even turning out to be a video game character! Much to her surprise, Claire finds herself periodically teleported to modern-day Tokyo where Claire Martino is no more than a side character in the classic dating sim game Upstart: Eternal Love. Yet even that won’t stop Claire from saving the day so she can unlock the good ending of her own route. less

Rebuilding from the ground up is old hat to Claire Martino after falling out of societal favor in her homeland and arising from the ashes as a hero in a neighboring kingdom. Therefore, when tragedy strikes due to her half-sister’s malicious scheming, Claire doesn’t think twice about going back in time to set things right. However, two can play at that game...Against old and new enemies alike, Claire is in for more trouble than ever before... moreRebuilding from the ground up is old hat to Claire Martino after falling out of societal favor in her homeland and arising from the ashes as a hero in a neighboring kingdom. Therefore, when tragedy strikes due to her half-sister’s malicious scheming, Claire doesn’t think twice about going back in time to set things right. However, two can play at that game...Against old and new enemies alike, Claire is in for more trouble than ever before. Fortunately, with her quick wits, unshakable resolve, and trusty team of allies, she remains determined to unlock the good ending. With the power of the Paffuto Kingdom at her back, can she beat Charlotte at her own game? And while Charlotte pursues her own love interest, can Claire reignite the spark she shared with Vik? less

Betrothed to Prince Asbert of the great kingdom of Noston, Claire is shocked when the engagement is suddenly annulled. More than that, the new consort to the throne is none other than her sister, Charlotte! As the daughter of the now disgraced duke and scorned as a villainess, Claire leaves everything she knows and sets out on a journey to find her true self.But wait, isn't that's the plot of the game "Upstart ♡ ETERNAL LOVE" on its hardest difficult setting...?