In this game world I played obsessively in my past life, I am going all out in the body of a young princess! In the Kingdom of Forland, royalty is granted a Divine Instrument through a sacred summoning ceremony held only once in a lifetime. Just moments before her own ceremony, the ten-year-old Princess Ashulina regains memories of her past life. She knows this world inside out as a game, one she had cleared to absolute completion. "Expecting me to pull a jackpot on a single gacha roll is totally insane, isn't it...?" And true to her worst fears, what Ashulina summons is a mere Rarity ★1 wooden sword. Amidst universal disappointment, she is cast aside and imprisoned in a remote, ancient fortress, erased as though such a princess had never existed in the first place... Yet she alone knows the truth through her past-life knowledge: with enough proficiency grinding, this humble wooden sword turns into something monstrous...! Determined to get payback against the royal family that abandoned her, this mere ten-year-old girl arms herself with past knowledge, sheer effort, and relentless grit to evolve into a legendary swordmaster and dominate alongside her companions!