Yucie, a seemingly ordinary 17-year-old, has yet to hit puberty and remains physically childlike. Despite her age, the stagnant growth of her body leaves her yearning for maturity. Unexpectedly, Yucie is selected as a contender for the distinguished "Platinum Princess" title - a once-in-a-millennium honor bestowed upon the worthy wearer of the fabled Eternal Tiara, rumored to grant its possessor anything they desire. However, she is not alone in her aspirations, as four other rivals compete for the coveted prize. To achieve her dream, Yucie enrolls at Princess Academy to develop her character and earn eligibility for the Eternal Tiara. With the support of her family, competitors, and the academy principal, will Yucie finally come of age as she desires?