Tradition: Chinese Mythology
Alternative Names: 龟毛兔角, Turtle Hair and Rabbit Horns, Tortoise-Furred Rabbit Horns
Category: Rabbit
The Myth
Tokaku refers to the expression “turtle hair and rabbit horns,” describing two impossible phenomena: turtles growing hair and rabbits developing horns. According to the Soushen Ji, drawing on works such as the Wuxing Zhi and Jingbo Yi Zhuan, unusual occurrences in nature were sometimes interpreted as ominous signs for the state. During the reign of King Zhou of Shang, a large turtle was said to have grown hair and rabbits were said to have grown horns. These phenomena were regarded as portents of war.
The expression subsequently became a metaphor for things considered impossible or beyond ordinary understanding. A similar expression, “black crow and white horse horns” (烏白馬角), likewise describes unnatural combinations that cannot exist in the ordinary world. Both expressions use extraordinary physical features to represent events that defy common sense.
In Buddhist writings, turtle hair and rabbit horns also serve as examples of things that exist in name but have no actual substance. Texts such as the Mahāprajñāpāramitā Śāstra and Mohe Zhiguan employ the imagery to explain the emptiness of all phenomena, teaching that neither the self nor other things possess a fixed, independently attainable existence. Other Buddhist works similarly list turtle hair, rabbit horns, and other nonexistent things as illustrations of the insubstantial nature of reality.
Sources
“Tokaku.” 新版TYZ 妖怪図鑑 (New TYZ Yokai Encyclopedia). https://tyz-yokai.blog.jp/archives/1084081649.html