"Earthian" is a science fiction anime series based on the manga by Yun Kouga. The narrative is set in a future where Earth is monitored by angels from the planet Eden, who evaluate humanity's worthiness for survival. The story primarily revolves around two main characters: Chihaya, a stoic and dedicated angel, and Kagetsuya, his more compassionate and empathetic partner. Together, they are part of a team known as the Earthian Angels, tasked with observing and reporting on human behavior.

The series explores themes of morality, identity, and the consequences of human actions. Chihaya and Kagetsuya are sent to Earth to investigate various incidents, often involving conflicts between humans and the ethical dilemmas they face. Their missions frequently bring them into contact with individuals whose actions challenge their understanding of humanity's value. Chihaya, who initially adheres strictly to his duty, begins to question the rigid judgments imposed by Eden, while Kagetsuya's inherent empathy for humans often puts him at odds with their mission's objectives.

A significant subplot involves the discovery of genetically engineered humans known as the "Els," who possess extraordinary abilities but are ostracized and hunted by society. The Els' existence raises questions about humanity's capacity for both creation and destruction, as well as the ethical implications of genetic manipulation. Chihaya and Kagetsuya's interactions with the Els further complicate their mission, as they grapple with the moral ambiguity of their roles as judges of humanity.

The series also delves into the personal dynamics between Chihaya and Kagetsuya, whose contrasting personalities and perspectives create a compelling partnership. Their evolving relationship is central to the narrative, as they navigate the challenges of their mission and their own internal conflicts. The story is punctuated by moments of action, introspection, and emotional depth, as the characters confront the complexities of their roles and the broader implications of their work.

"Earthian" presents a thought-provoking exploration of humanity's potential for both good and evil, framed within a futuristic and morally ambiguous setting. The interplay between its central characters and the ethical dilemmas they face drives the narrative, offering a nuanced portrayal of the challenges inherent in judging the worth of an entire species.