A brief description of the Wortenia Senki manga:
Mikoshiba Ryouma was called to another world, and this during the war. He is also a high school student. Unexpected turn. The guy was seriously angry at the culprit of these events. Responsible for the call is a worker in the O’Ltome Empire. With the help of combat skills, Remus escapes from the army, not forgetting to kill the key figures of the empire. In the end, he saves two sisters and snatches them from the hands of the kidnappers. The twins, as it turned out, can and practice magic. In gratitude for the help, they swear to him to serve faithfully. So Rema begins his journey to the supreme ruler.