"Needless+: Saint Lily Gakuen no Himitsu" is a short anime series that serves as a spin-off of the original "Needless" franchise. The story is set in Saint Lily Gakuen, an all-girls academy where students possess unique abilities known as "Fragments." These Fragments grant them supernatural powers, and the academy serves as a training ground for these gifted individuals. The narrative centers around a group of students who form the "Needless+ Team," tasked with investigating and resolving mysterious incidents within the school.

The protagonist, Eve Neuschwanstein, is a transfer student with a mysterious past and a powerful Fragment ability. She quickly becomes the focal point of the team, which includes other key members such as Setsuna, a skilled swordswoman with a stoic demeanor, and Mio, a cheerful and energetic girl with a knack for technology. Together, they uncover secrets about the academy, including hidden experiments and the true nature of Fragments. The plot intertwines action, comedy, and elements of mystery as the team faces various challenges, including rival factions within the school and external threats.

The series explores themes of friendship, teamwork, and the ethical implications of wielding extraordinary powers. Each episode delves into the personal struggles and growth of the characters, while also advancing the overarching plot. The dynamic between the team members is a central focus, with their interactions providing both comedic relief and emotional depth. The narrative builds toward a climactic confrontation that tests their abilities and resolve, ultimately revealing deeper truths about the academy and their own identities.