"Lapis Re:LiGHTs" is set in a world where magic is an integral part of society, and young girls train to become magical idols known as "Witches." The story centers on Tiara, a cheerful and determined girl who enrolls at the prestigious Flora Girls' Academy, a school dedicated to nurturing Witches. Tiara dreams of becoming a top idol, but her journey is far from easy. The academy is divided into units, each consisting of a group of students who work together to hone their magical and performance skills. Tiara joins the unit "LiGHTs," which includes her childhood friend Rosetta, the serious and disciplined Lavie, the energetic and mischievous Ashley, and the shy but talented Lynette.

As the series progresses, Tiara and her unitmates face various challenges, both personal and external. They must balance their studies, magical training, and idol performances while navigating the competitive environment of the academy. The narrative explores themes of friendship, perseverance, and self-discovery as the members of LiGHTs grow closer and learn to rely on each other. Their journey is marked by performances at magical festivals, where they showcase their abilities and compete against other units, including the elite group "IV KLORE," known for their exceptional talent and high standards.

The plot takes a darker turn when a mysterious phenomenon known as the "Starfall" begins to threaten the world. This event disrupts the balance of magic and poses a significant danger to both Witches and the general population. Tiara and her friends are drawn into the mystery surrounding Starfall, uncovering secrets about its origins and the true nature of their magical abilities. The series blends elements of magical girl tropes with idol culture, creating a unique narrative that combines lighthearted moments with more serious, high-stakes scenarios.

Throughout the series, the characters' relationships and individual growth are central to the story. Tiara's unwavering optimism and determination inspire her friends, while each member of LiGHTs confronts their own insecurities and aspirations. The dynamic between the characters drives the narrative forward, emphasizing the importance of teamwork and mutual support. The series concludes with a resolution to the immediate threat of Starfall, but leaves room for further exploration of the world and its characters, hinting at future challenges and adventures for Tiara and her friends.