A simian-form apparition modeled on Sekien Toriyama’s Konjaku Gazu Zoku Hyakki entry and natural-historical notes in Sino-Japanese texts. It appears on remote mountain paths, instantly voices the thoughts of woodcutters and travelers, and gauges their behavior. Disinclined to harm humans, it withdraws swiftly when sensing danger, in line with Sekien’s text. In folktales its figure varies by region—monkey, mountain man, tengu, or tanuki—but its core is “mind reading” and retreating at sudden noises. Its mind reading mirrors the other’s thoughts and repeats them, closer to a warning than provocation. It reads presences in mountain stillness yet proves vulnerable to the unexpected—sparks from a campfire or a flying splinter. The name Kakku is linked to the character 玃 through phonetic conflation, from which an independent yokai image emerged. Traditions span Chubu to Kanto, Tohoku, Chugoku, and Kyushu, telling of a being that measures the boundary between people and the otherworld in the mountains.