Shaped by experiences that left him weary of human relationships, Rei Hitoma openly dislikes people. Seeking a quiet, uneventful life, he accepts a teaching position at a secluded school in the mountains, only to discover that his classroom is anything but ordinary. The students under his care are demi-humans who have gathered there with a singular goal: to learn what it means to become human. Despite his disillusionment, Rei finds himself responsible for explaining human behavior and social norms to mermaids, bunnies, werewolves, and the like. As his students earnestly struggle to understand humanity, their questions and aspirations gradually expose the contradictions in Rei's own beliefs.

It is the year 2100, and on the colonized Moon, a project is under way to explore new aspects of energy. Amami Kurau is the daughter of the chief scientist on the project, and on her 12th birthday, she accompanies her father to the lab to observe the experiments. Then something goes awry, and Kurau is struck by twin bolts of light. In the aftermath, her father is dismayed to find that his daughter is no longer his daughter. Rather, her body is now home to two energy entities with fantastic powers. (Source: ANN)

Before Chise became the ultimate weapon, there was another—Lieutenant Mizuki. A battle-hardened military woman, she volunteered for an experimental procedure after injuries left her unable to return to the battlefield. As the prototype ultimate weapon, Lieutenant Mizuki was highly successful on the battlefield, however, as the first candidate, her development was limited. When a more suitable candidate to become the weapon, Chise, is forced into the military, Lieutenant Mizuki thinks that she is silly, weak, and unsuited for the role. As the only other person to have undergone the procedure, however, Lieutenant Mizuki can hear Chise's thoughts and is the only one who understands her. As the war rages on and Chise's development progresses, Lieutenant Mizuki discovers more about Chise, ultimate weapons, and herself.

A dog named Weed happens to hear that he is the son of Gin, the great leader of Ohu who lead the dogs of Ohu to victory in a fight against monsterous bear, Akakabuto. Weed wants to find his father no matter what. On a journey to find his father Weed meets many friends and enemies. (Source: ANN)