Koga-ryu is a traditional school of Japanese ninjutsu that originated in the Koga region, now part of Shiga Prefecture. It is known for its emphasis on stealth, espionage, and guerrilla warfare techniques. The school incorporates various martial arts, including taijutsu (unarmed combat), kenjutsu (sword techniques), and shurikenjutsu (throwing weapons). Founded during the Feudal Era of Japan, Koga-ryu practitioners were often employed as spies and assassins. The techniques and philosophies of Koga-ryu have been passed down through generations, and today, it is studied by martial artists interested in historical combat practices and the art of ninjutsu.