"Kotodama Shōjo the Animation: Microphone Soul Spinners" centers around a unique blend of psychological thriller and supernatural elements, set in a high school environment. The story revolves around the concept of "kotodama," a Japanese belief in the spiritual power of words, which is weaponized through a mysterious app called "Microphone Soul Spinners." This app allows users to manipulate others by speaking specific phrases into their smartphones, effectively controlling their thoughts and actions. The narrative explores the consequences of this power and the moral dilemmas it creates.

The protagonist, Koto Amatsuka, is a reserved and introverted high school student who stumbles upon the app. Initially skeptical, she becomes entangled in its dark potential after witnessing its effects firsthand. As Koto begins to experiment with the app, she discovers that its power is not without cost—each use exacts a toll on the user's psyche, blurring the line between reality and illusion. The app also attracts the attention of other students, each with their own motivations for wielding its power, leading to a series of escalating conflicts.

Key characters include Koto's classmates, such as the enigmatic and manipulative Aine Shizukawa, who becomes both an ally and a rival in Koto's journey. Aine's motivations are complex, driven by a desire to uncover the truth behind the app's origins and its connection to a tragic incident in her past. Another significant figure is Rui Kisaragi, a cheerful and outgoing student who initially appears unaffected by the app but gradually reveals a deeper connection to its workings. The interactions between these characters form the core of the narrative, as alliances shift and secrets are uncovered.

The plot delves into themes of control, identity, and the ethical implications of power, as the characters grapple with the consequences of their actions. The app's influence spreads beyond the school, drawing in external forces that seek to exploit its capabilities for their own ends. As Koto and her peers navigate this dangerous landscape, they must confront not only external threats but also their own inner struggles, as the app's power begins to erode their sense of self.

The series builds toward a climactic confrontation, where the true nature of the app and its creators is revealed. The resolution ties together the various narrative threads, offering a conclusion that underscores the series' exploration of the power of words and the fragility of human perception. Through its intricate plot and character dynamics, "Kotodama Shōjo the Animation: Microphone Soul Spinners" presents a thought-provoking examination of the intersection between technology, morality, and the human condition.