Above all else, Sena Narumi adores her little sister, Mona. However, they both have their own dreams: Sena rises to stardom through modeling, while Mona wants to become a beloved idol. Although they both have the talent to succeed, Mona feels left behind in the wake of her sister's success. Even so, Sena resolves to be the best big sister she can be, all while being the biggest fan of Mona—her angel.