Dengu is a mysterious and imaginary creature. Originally, it was a monster which looked like a bird flying with its wings. This image was recorded in Gonjakumonokatarisyu which was published in the Heian period and gave the detailed description. Its appearance and characteristic have changed period after period, but it was a heretic toBuddhismaccordingtotheGonjakumonokatarisyu. In Gonjakumonokatarisyu, Dengu is described as a wicked creature which tried to block spread of Buddhism. Most of Buddhist stories came from many documents and Buddhist scriptures written in India. Since the Buddhism was brought into China, Korea, and Japan, many Buddhist stories have been created. Because those stories were made as Buddhism was transferred, yaksha and rakshasha, which are monsters in Buddhist scriptures, are thought to be linked to Dengu. So we can make an analogy between these monsters in the Buddhist scriptures and Dengu. In the Buddhist scriptures, yaksha and rakshasha appear as monsters which bully people and harass Buddha in his practice. One thing in common between those monsters in the Buddhist scriptures and Dengu is that they are depicted as obstructers who try to disturb Buddhist ascetics in practices. So Dengu, as a heretic to Buddhism, is considered to have been created under the influence of monsters in Buddhist scriptures.