"Devils' Line II: Gyakushū" is a continuation of the original "Devils' Line" series, expanding on its supernatural and societal themes. The story is set in a world where vampires, referred to as "devils," coexist with humans. These devils possess heightened physical abilities and an insatiable thirst for human blood, which they must resist to maintain their humanity. The narrative explores the fragile balance between humans and devils, as well as the moral and ethical dilemmas arising from their coexistence.

The protagonist, Tsukasa Taira, is a human college student who becomes romantically involved with Anzai, a half-devil working for a secret police unit tasked with monitoring and controlling devils. Their relationship faces constant challenges due to Anzai's struggle to suppress his bloodlust and the societal stigma surrounding their bond. As the story progresses, Tsukasa and Anzai navigate the complexities of their relationship while confronting external threats from extremist groups and rogue devils.

The sequel, "Devils' Line II: Gyakushū," delves deeper into the political and social tensions between humans and devils. A new antagonist emerges, seeking to exploit the divide between the two groups for personal gain. This figure manipulates public opinion and incites violence, leading to heightened conflict and mistrust. The narrative also introduces additional characters, including other half-devils and members of the police unit, who provide further insight into the struggles faced by those caught between both worlds.

Themes of identity, prejudice, and the nature of humanity are central to the story. The series examines how societal fear and misunderstanding can lead to discrimination and violence, while also highlighting the potential for empathy and cooperation between humans and devils. The characters' personal journeys are intertwined with the larger societal issues, creating a layered and thought-provoking narrative.

"Devils' Line II: Gyakushū" maintains the tension and emotional depth of its predecessor, offering a compelling exploration of its central themes. The story balances action, romance, and social commentary, making it a notable entry in the supernatural genre.