Horn Disease

In a strange world where danger hides behind the appearances of gentleness and tranquillity, the little ageless ninja Kurihara discovers one fine day he's suffering from a bizarre disease whom known only symptom is the appearance on the top of the skull of a small horn. It transports Kurihara in an unknown world... where everything looks exactly like the one he has just left but with abound improbable enemies eagerly awaiting our little ninja...