Kaso stands for "fiery rat," known as Huo Shu (火鼠) in China. It was made famous by the folklore the Tale of the Bamboo Cutter (竹取物語) 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."
—Shin Megami Tensei: Strange Journey compendium
Shin Megami Tensei IV[]
"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 Monogatarui," Princess Kaguya asks one of her suitors to obtain a robe made from the fur."
—Shin Megami Tensei IV profile
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.
Shin Megami Tensei IV Apocalypse[]
"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 profile
Kaso appears throughout the Ueno area. It can provide the Agi and Sukukaja skills during the Demon Whisper event.
Devil Summoner: Soul Hackers[]
"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."
—Devil Summoner: Soul Hackers 3DS compendium
DemiKids Light / Dark Version[]
"Rat-like demon with skin of burning flames. Often found sleeping in volcanos."
—Demonary entry
Known as Lava Rat in the games.
Devil Children Messiah Riser[]
S-Rank Kaso can be obtained on Jin's route in the world of Fire Makai, where they are gifts from any story battle that gets Ranked S.
