Ryōgen is known generally by the names of Gansan Daishi (left) or Tsuno Daishi (right). The figure of Tsuno Daishi (Horned Great Master) is said to be a portrait of him subjugating vengeful ghosts
The Horned Great Master in Engelbert Kaempfer's History of Japan (1727). On his way to Edo in 1691 Engelbert Kaempfer saw these paper glued to doorposts of many houses. His description published in the History of Japan is correct, but he wrongly called it Gozu Tennō (Ox-head-heaven-king), a deity worshiped at the Gion Shrine (Yasaka Jinja) in Kyotō.
Talisman showing Ryōgen (912-985) as the Horned Great Master
Ryōgen(良源?, 912 – January 31, 985 AD) was a chief abbot of Enryaku-Temple (Enryaku-ji) in the 10th century, and the founder of the tradition of warrior monks (sōhei).
Over the course of the 10th century, there had been a number of disputes between Enryaku-ji and the other temples and shrines of the Kyōto area, many of which were resolved by force. In 970, Ryōgen formed a small army to defend Enryaku-Temple and to serve its interests in these disputes. Records are not fully clear on whether this army consisted of hired mercenaries, or, as would be the case later, trained monks. Most likely, this first temple standing army was a mercenary group, separate from the monks, since Ryōgen forbade monks from carrying weapons.
In addition to the prohibition on carrying weapons, Ryōgen's monks were subject to a list of 26 articles released by Ryōgen in 970; they were forbidden from covering their faces, inflicting corporal punishment, violently interrupting prayer services, or leaving Mount Hiei during their 12-year training.