Martin Tachibana is a San Francisco-based biotechnology scientist. His experiments produce Neo-Aragami, artificial creatures devoid of the mythological Susanoo's power. These creations unleash destruction across California, forcing the Terrestrial Administration Center to intervene.

He is the father of Valencia Tachibana, a character appearing in the sequel OVA. Like Mamoru Kusanagi, Valencia possesses a mitama implant without fully becoming an Aragami, indicating a familial link to supernatural elements within the series. Martin's appearance features grey hair, black eyes, and facial hair, reflecting his age and profession, alongside a combined American and Japanese heritage.

Martin's actions directly trigger the OVA's central conflict, making him the catalyst for the resurgence of threats confronting the protagonists. His renegade scientific work represents a shift in the Aragami threat's origin, moving from mythology to biotechnology.