"Betterman" is a 26-episode anime series that blends elements of science fiction, psychological horror, and mecha. The story is set in a near-future world where humanity faces existential threats from mysterious phenomena known as "Alterations," which cause bizarre mutations and psychological disturbances. These events are linked to a mysterious entity called "Betterman," a bio-mechanical being with ambiguous motives.

The protagonist, Keita Aono, is a young engineer working for the Neuron Corporation, a company specializing in advanced robotics and neural technology. Keita becomes entangled in the unfolding crisis when his childhood friend, Hinoki Sai, is affected by an Alteration. Hinoki's condition worsens, leading Keita to seek answers about the nature of these phenomena and the role of Betterman. Along the way, Keita encounters a group of scientists and pilots who operate advanced mecha called "Akamatsu Units," designed to combat the Altered creatures.

As the series progresses, it is revealed that Betterman is connected to a larger conspiracy involving the evolution of humanity and the emergence of a new form of consciousness. The narrative explores themes of human identity, the boundaries between organic and artificial life, and the ethical implications of technological advancement. Key characters include Lamia, a mysterious girl with a deep connection to Betterman, and Sakura, a scientist who provides critical insights into the Altered phenomena.

The plot intertwines personal struggles with broader existential questions, as Keita and his allies confront both external threats and internal conflicts. The series builds toward a climactic revelation about the true nature of Betterman and its relationship to humanity's future. Through its intricate storyline and exploration of complex themes, "Betterman" offers a thought-provoking narrative that challenges conventional notions of life, consciousness, and evolution.