Set in 1923 Tokyo, "MARS RED" explores a world where vampires coexist with humans, though their presence is increasingly regulated by the government. The narrative centers on the Code Zero unit, a secret military task force established to manage vampire-related threats. The unit is composed of both human soldiers and vampire operatives, creating a dynamic interplay of loyalty, power, and morality. The story begins with the sudden appearance of artificial blood sources, known as Ascra, which disrupt the delicate balance between humans and vampires. This development leads to widespread societal upheaval, as vampires no longer need to rely on humans for sustenance, and humans grow increasingly wary of their immortal counterparts.

The protagonist, Lieutenant Yoshinobu Maeda, is a human officer tasked with leading Code Zero. His leadership is tested as he navigates the complexities of commanding a unit that includes vampires, particularly his former comrade, Kurusu, who was turned into a vampire during a mission. Kurusu’s transformation serves as a focal point for exploring themes of identity, loss, and the blurred lines between humanity and monstrosity. Another key character is Suwa, a vampire with a tragic past who struggles with his own sense of purpose and morality. The interactions between these characters drive much of the emotional and philosophical tension within the series.

As the story progresses, Code Zero investigates a series of incidents tied to the spread of Ascra and the emergence of a powerful vampire faction seeking to overthrow human dominance. The narrative delves into the political machinations of both human and vampire societies, highlighting the fragile alliances and deep-seated mistrust between the two groups. The series also incorporates elements of mystery and intrigue, as the origins of Ascra and the true motives of key figures are gradually revealed.

The setting of 1920s Tokyo is integral to the story, with its blend of traditional Japanese culture and rapid modernization serving as a backdrop for the conflict. The series incorporates historical and cultural references, adding depth to its world-building. The pacing is deliberate, with a focus on character development and the exploration of moral dilemmas rather than action-heavy sequences. This approach allows for a nuanced examination of the ethical questions surrounding coexistence, power, and the nature of humanity.

Overall, "MARS RED" presents a layered narrative that combines supernatural elements with historical and political intrigue. Its exploration of the relationships between humans and vampires, as well as the personal struggles of its characters, creates a compelling and thought-provoking story.