Kaso, also known as Huo Shu (火鼠) in China, was made famous by the folklore the Tale of the Bamboo Cutter in which Kaguya requires one of her suitors to bring the robe of Kaso fur to her for her hand in marriage. This suitor instead brings a fake to Kaguya, she then throws the robe into the fire, exposing the counterfeit because the real one is said to be incombustible.
"A rat said to live in fire in ancient Chinese myths. The fur of these creatures is said to never burn in fire. In the Japanese story "Taketori Monogatari," Princess Kaguya asks one of her suitors to obtain a robe made from the fur."
Kaso can be found in Kasumigaseki. It can teach Flynn Agi and Sukukaja through its Demon Whisper. Kaso must be hunted for Kaso's Hide in the Challenge Quest "Creating Fireproof Clothing." After collecting 4 Kaso's Hide items, they must be turned in to K's Tavern in order to unlock the Fire Guard body armor at Q's Blacksmith.
"A rat said to live in fire in ancient Chinese lore. The fur of these creatures is said to never burn in fire. In the Japanese story "Taketori Monogatari," Princess Kaguya asks for one of her suitors to obtain a robe made from the fur."
—Shin Megami Tensei IV Apocalypse compendium
Kaso appears throughout the Ueno area. It can provide the Agi and Sukukaja skills during the Demon Whisper event.
"A rat that ancient Chinese myths claimed lived in fire. The fur of these creatures is said to be incombustible. In the Japanese story "Taketori Monogatari," Princess Kaguya asks one of her suitors to obtain a robe made from their fur."
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