"Kishin Corps" is set in an alternate history during World War II, where humanity faces a dire threat from supernatural beings known as Youkai. These malevolent entities, originating from Japanese folklore, have begun to wreak havoc across the globe, prompting nations to develop advanced technology and military strategies to combat them. The story centers on the Kishin Corps, a secret Japanese military unit tasked with piloting giant mechanical robots called Kishin to fight the Youkai. These robots are powered by a mysterious energy source known as "Kishin Energy," which grants them immense power but also poses significant risks to their pilots.

The narrative follows Captain Shougo Yahagi, a skilled and determined leader of the Kishin Corps, as he commands his team in battles against the Youkai. Alongside him are several key characters, including Lieutenant Colonel Kenjiro Taki, a seasoned officer with a deep understanding of the Youkai threat, and Shizuka Tokito, a talented engineer responsible for maintaining and upgrading the Kishin. The team also includes a diverse group of pilots, each with their own motivations and struggles, as they face the physical and psychological toll of piloting the Kishin.

As the war against the Youkai intensifies, the Kishin Corps uncovers a deeper conspiracy involving the origins of the Youkai and the true nature of Kishin Energy. The story explores themes of sacrifice, loyalty, and the moral complexities of warfare, as the characters grapple with the consequences of their actions and the blurred lines between humanity and monstrosity. The series blends historical elements with science fiction and supernatural themes, creating a unique narrative that examines the intersection of technology, mythology, and human resilience in the face of overwhelming odds.