When a meek-hearted Akira Fudou joins forces with his childhood friend Ryou Asuka to confront devils, they stumble upon a debaucherous gathering where demonic possession unleashes chaos. In a daring move to rescue Ryou, Akira merges with the demon Amon, transforming into a Devilman with the strength to battle the malevolent entities. Balancing newfound power with his compassionate nature, Akira navigates a world where he must protect humanity while struggling with his inner devilish instincts.