"Depravity" is a psychological thriller anime that explores themes of morality, identity, and the consequences of unchecked ambition. The narrative centers on Kaito Arashi, a brilliant but disillusioned college student who becomes entangled in a clandestine experiment after encountering a mysterious organization known as the Erebus Foundation. The foundation claims to offer participants the ability to unlock their full potential through a revolutionary procedure called the "Ascension Protocol." However, the procedure comes with unforeseen side effects, including severe psychological deterioration and the emergence of alternate, darker personalities.

As Kaito undergoes the protocol, he begins to experience fragmented memories and visions, blurring the line between reality and illusion. His relationships with those around him, including his childhood friend Aya Nakamura and his estranged mentor Dr. Renjiro Takagi, grow increasingly strained as his behavior becomes erratic and unpredictable. The story delves into Kaito's internal struggle as he grapples with the ethical implications of the experiment and the growing influence of his alternate self, who embodies his suppressed desires and darkest impulses.

The Erebus Foundation, led by the enigmatic Dr. Evelyn Cross, is revealed to have a hidden agenda tied to a larger conspiracy involving human experimentation and the pursuit of transcendence. As Kaito uncovers the truth, he must confront not only the foundation but also the darker aspects of his own psyche. The narrative is punctuated by intense psychological battles, moral dilemmas, and a series of twists that challenge the characters' perceptions of free will and humanity.

Supporting characters, such as the pragmatic hacker Rina Fujimoto and the morally ambiguous scientist Dr. Cross, add depth to the story, each contributing to the unfolding mystery and the escalating tension. The plot builds toward a climactic confrontation where Kaito must decide whether to embrace his newfound power at the cost of his humanity or reject it and face the consequences of his choices. The series concludes with an ambiguous yet thought-provoking resolution, leaving the ultimate fate of Kaito and the Erebus Foundation open to interpretation.