"Biohazard: Heavenly Island" is a manga series set in the "Resident Evil" universe, written and illustrated by Naoki Serizawa. The story takes place in 2014, several years after the events of "Resident Evil 6," and follows Claire Redfield as she investigates a mysterious island while working for the anti-bioterrorism organization TerraSave. The narrative begins with Claire and her team arriving on Sushestvovanie Island, a remote location rumored to be conducting illegal bioweapon experiments. The island is shrouded in secrecy, and its inhabitants exhibit strange behavior, hinting at a deeper, darker conspiracy.

Claire's investigation leads her to uncover the island's connection to a new strain of the T-virus, developed by a rogue faction within the Umbrella Corporation. This strain, known as the "T-Phobos Virus," induces extreme fear in its victims, triggering mutations that transform them into monstrous creatures. The virus is tied to a research project led by Dr. Glenn Arias, a former Umbrella scientist seeking revenge for the death of his family during the Raccoon City incident. Arias aims to weaponize the virus on a global scale, using the island as a testing ground.

As Claire delves deeper, she encounters a group of survivors, including a young girl named Moira Burton, who has a personal connection to the island's experiments. Moira, the daughter of Barry Burton, plays a pivotal role in uncovering the truth about the T-Phobos Virus and its origins. The narrative explores themes of survival, betrayal, and the ethical implications of bioweapon research, as Claire and her allies confront both the infected creatures and the human conspirators behind the outbreak.

The story builds toward a climactic confrontation with Arias, who has transformed himself into a powerful bio-organic weapon using the T-Phobos Virus. Claire and Moira must work together to stop Arias and prevent the virus from spreading beyond the island. The manga concludes with the destruction of the island's research facilities, but leaves lingering questions about the future of bioterrorism and the ongoing threat posed by Umbrella's remnants.

Throughout the series, the narrative maintains a tense, action-driven pace, blending horror elements with the established lore of the "Resident Evil" franchise. The characters' motivations and relationships are explored in the context of the overarching conflict, providing depth to their roles in the story. "Biohazard: Heavenly Island" serves as a standalone entry in the franchise while contributing to the larger narrative of the "Resident Evil" universe.