Kōga-ryū
Kōga-ryū (甲賀流, "School of Kōga") is an umbrella term for a set of traditions of ninjutsu that originated from the region of Kōga (now the city Kōka in Shiga Prefecture). The samurai of Kōga-ryū were known as "Kōga-no-mono", and operated as shinobi throughout Japan's turbulent Sengoku period.