"Baggy" is a 12-episode anime series that blends elements of science fiction, mystery, and psychological drama. The narrative centers on a young man named Haruto, who discovers a sentient, shape-shifting entity named Baggy after a mysterious meteor crash near his rural hometown. Baggy, a gelatinous, amorphous being, bonds with Haruto, granting him extraordinary abilities, including enhanced strength, agility, and the capacity to morph parts of his body. However, this symbiotic relationship comes with a cost: Haruto begins experiencing vivid, fragmented memories that do not belong to him, hinting at a deeper connection between Baggy and humanity’s past.

As Haruto grapples with these intrusive memories, he learns that Baggy is not the only entity of its kind. Other individuals across the globe have also bonded with similar beings, each manifesting unique powers. These hosts, referred to as "Symbiotes," are drawn into a clandestine conflict orchestrated by a shadowy organization known as the Nexus Foundation. The Foundation seeks to harness the entities' abilities for their own agenda, which involves unlocking a hidden truth about the origins of these beings and their purpose on Earth. Haruto, alongside a small group of fellow Symbiotes, must navigate this dangerous landscape while uncovering the truth about Baggy’s origins and the impending threat to humanity.

The series explores themes of identity, memory, and the ethical implications of power. Haruto’s journey is marked by internal conflict as he struggles to reconcile his humanity with the growing influence of Baggy. Supporting characters, such as Aiko, a fellow Symbiote with the ability to manipulate energy, and Ren, a rogue agent working against the Nexus Foundation, add depth to the narrative. Their interactions highlight the moral dilemmas and personal sacrifices inherent in their shared predicament. The plot builds toward a climactic confrontation with the Nexus Foundation, revealing the true nature of the entities and their connection to an ancient, extraterrestrial civilization. The series concludes with an open-ended resolution, leaving room for potential exploration of its richly constructed world.