Mount Omine Cave - Pseudo-Goki

The Last Word of Nitori Kawashiro from the world reborn (a Touhou LW original). She replicates the legendary blue oni shikigami's power. The blue oni, Goki, is shrouded in mystery and is said to be either Zenki's partner or wife, depending on the tale. This is exactly like Ibaraki-Douji's relationship with Shuten-Douji. The oni, tengu, and kappa are said to be the largest three subspecies of youkai, but distinguishing between them has always been a challenge. There are many definitions and origins of oni, with the broadest definition labeling them as any being that lives on after death and that wields mysterious magic or overwhelming power. As it happens, such a definition would include all youkai. In particular, tengu, who are the mysterious nature of the mountains given form, and kappa, who loosely represent death near water, are both youkai who could easily be classified as oni. In essence, the lines between the subspecies of oni, tengu, and kappa were all drawn using the later-devised fields of semiotics and biology, and have no connection to the youkai themselves.

Hebo is said to be the progenitor of kappa, and far from being a kishin from the Taoist viewpoint, he's a literal god who accumulates a great deal of faith. These connections are very old, but they were enough for the two-stage shikigami summoning process to succeed.