"Pet" is a psychological thriller anime that explores the manipulation of memories and the intricate dynamics of human relationships. The story revolves around a secret organization that trains individuals, referred to as "Pets," to infiltrate and alter the memories of their targets. These Pets possess the ability to enter the minds of others, navigating their subconscious to erase or rewrite memories, often for the benefit of the organization's clandestine operations.

The narrative primarily follows Tsukasa, a skilled Pet who works alongside his partner, Hiroki, under the guidance of their mentor, Satoru. Tsukasa and Hiroki share a deep bond, having grown up together within the organization. However, their relationship becomes strained as the story delves into their past, revealing layers of manipulation and betrayal. The organization's methods of control are ruthless, and the line between reality and altered memories becomes increasingly blurred, raising questions about identity, trust, and free will.

As the plot progresses, Tsukasa and Hiroki are drawn into a complex web of power struggles within the organization. They encounter other Pets, each with their own motivations and conflicts, further complicating their mission. The series examines the psychological toll of memory manipulation, both on the targets and the Pets themselves, as they grapple with the consequences of their actions. Themes of loyalty, autonomy, and the fragility of the human mind are central to the narrative.

The anime employs a non-linear storytelling approach, frequently shifting between past and present to unravel the characters' histories and the true nature of their abilities. This structure enhances the tension and mystery, keeping viewers engaged as the layers of the story are gradually revealed. The interplay between the characters' personal struggles and the larger machinations of the organization creates a compelling narrative that balances emotional depth with suspenseful intrigue.