It’s a medieval Japanese school of martial arts allegedly established in the 16th century by Uryu Hangan Gikanbo. Gikan-Ryu Koppojutsu is based on martial arts skills and techniques that Uryu Hangan Gikanbo learned from Sougyoku Kan Ritsushi, Soke of Gyokko-Ryu Kosshijutsu and Koto-Ryu Koppojutsu.