In the previous series "Kite," a killer—Sawa—suddenly disappears after she avenges her parents' death, and no one knows where she is. Several years later, a figure dances airily on the dark side of a big city. She is an angel of death, killing her victim gracefully and disappearing. Monaka is a normal high school student, though this quiet and modest life has a darker side. An angel of death is Monaka's other persona.

The series is set in a near-future world where the boundary between human being and AI is vague. A rapid biological evolution, similar to "Cambrian Explosion," is caused by one incident. This incident turns into the genesis of a new jostle for supremacy, and the influence of the evolution goes beyond biological framework and spreads to various kinds of materials and technologies. The era of massive evolution involving diverse existences, such as human, machines, and biotechnologies, is coming. Characters fight an existential war in such a world. (Source: ANN)

Second season of Hangyakusei Million Arthur.

In the near future, robot technology has advanced to the point of self-awareness. Under the leadership of the "Black King," machines have decimated the human population and conquered the world. Those who survived the early holocaust have been enslaved for life. But throughout the hardships, a lone hero appears as the savior of mankind. He is Casshan - a fusion of man and machine driven to combat Black King and his forces to the end. (Source: ANN)