In "Hyakki Yagyo Emaki (picture scroll of a hundred specters strolling at night)", Yama-arashi is illustrated as a beast whose entire skin is covered with spines. Because no detailed description is attached to it, no one can be sure what kind of Yokai (specter) the Yama-arashi represents, but some say that the Yama-arashi is not Yokai but merely an illustrated figure of the real animal, porcupine (yama-arashi in Japanese), or that fragmented information that a porcupine uses its spines to threaten other animals created the fictitious Yokai, Yama-arashi.
Although the connection with the painted Yama-arashi has not been verified, there is folklore on Yokai (specter) Yama-arashi in various places across Japan,
In Arita County of Wakayama Prefecture (present-day Hirokawa Town, Wakayama Prefecture) and Yamagata County of Hiroshima Prefecture, Yama-arashi is also called 'Shii'; cow keepers often say 'Shii, Shii', meaning 'Yama-arashi is behind you', to move cows forward as cows are very scared of porcupines full of spines. In Daito Village, Yoshino County of Nara Prefecture, Yama-arashi is said to be a monster which makes noise of cutting trees in mountains.
In the literature from the Edo period, such as "Yamato-honzo", "Wakan Sansai Zue" and "Saikai Zokudan", Shii is written '黒眚' in Kanji, which means ''black disaster.''
According to "Yamato Honzo," ''Shii'' is said to have lived in Suo Province (present-day Yamaguchi Prefecture) and Tsukushi Province (present-day Fukuoka Prefecture), and to have harmed cattle and horses and it was not easy to catch as it was very smart and could move very fast. According to "Saikai Zokudan," it is said to have lived in Yoshino County of Nara Prefecture and could hurt face, arms and legs and even throat of humans just by touching the monster. Some people say that ''Shii'' was a Chinese monster in origin as often mentioned in Chinese folklore, and in Japan, ''Shii'' in the literature of the Edo period is merely an alias for unidentified monsters.