The Tsuchigumo (土蜘蛛*)? literally "earth spider", is a phrase with muddled history with its etymology, as there's debate which association for "tsuchigumo" came first: the spider-limbed monsters, or the pejorative used to refer against aborigines who did not show allegiance to the emperor of Japan, which came from even older pejorative, Tsuchigomori (土隠*)?, which was a reference to rural clans utilizing natural cave systems to created hollowed earth mounds for both residential and military purposes.
One tale regarding the youkai is a clash with it and Minamoto no Yorimitsu, also known as Raikou, which was depicted on the picture scroll Tsuchigumo Sōshi, where he and his retainer Watanabe no Tsuda followed a airborne skull into a house with an assortment of youkai, until a young woman attacks. Yorimitsu retailates and cuts the woman down, which fades away to reveal that he cut the foundation stone in twain, with his broken sword stained in white blood. They then followed the trail of white blood to another location, and found the tsuchigumo. After a fierce battle, the tsuchigumo was beheaded and gutted, spilling out well over a thousand skulls. They were given a proper burial and then set the house the Tsuchigumo was in aflame.
"Origin: Japan. An earth spirit from ancient times. It is a giant spider about 4 feet tall that lives in a mount at Kitano. They were defeated by Minamoto no Yorimitsu who later named his sword 'Spider Cutter.'"
—Shin Megami Tensei A-Mode DDS Dictionary
Shin Megami Tensei IV
"Monsters said to come from the bastardization of certain clans of Japan. The word comes from a different word, "tsuchigomori", meaning dirt-dweller. Those who did not pledge allegiance to the Imperial Court were called this because they lived in holes and caves. As time passed, people may have misinterpreted the name for a literal meaning and made them into spiders, or perhaps the manifestations of grudges of those who were put to death by the Imperial Court."
—Shin Megami Tensei IV profile
A Tsuchigumo is summoned by one of the Ashura-kai men in front of the elevator that leads to the Counter-Demon Force Base at Kagsumigaseki. The spider demon's defeat leads the men who summoned it to flee.
Tsuchigumo can later be found in the government office plaza area of Shinjuku among the Jirae clan demons that have occupied the area. After that, it can be found in Midtown and Reverse Hills. It can also be evolved from Ubu once Ubu reaches level 26. Tsuchigumo can teach Flynn the Poison Claw, Zionga and Me Patra skills through its Demon Whisper.
Tsuchigumo also appears in the "Hunter Tournament Prelims" Challenge Quest while supporting Flynn's second opponent, Commander Dynamo.
Shin Megami Tensei IV Apocalypse
Tsuchigumo can be found in the Sky Tower or it can be found by allowing Ubu to evolve at level 27. It can teach the Poison Claw, Zionga, Me Patra and Mazionga skills through its Demon Whisper. Tsuchigumo benefits from learning Electricity, Gun, ailment and healing skills.
Devil Summoner: Raidou Kuzunoha vs. The Soulless Army
"A wild god shaped like a giant spider, which was said to have lived in Mt. Katsuragi. Originally a native of the land who lived in a hole after its tribe was defeated by the Imperial Court."
—Devil Summoner: Raidou Kuzunoha vs The Soulless Army Devil Chart
A Tsuchigumo kidnaps Rin in order to distract Raidou Kuzunoha the XIV. Raidou travels to the Dark Realm of Tsukudo-Cho and fights three Tsuchigumo to save her. This is the first boss fight in the game. Recruiting Azumi in the area and leveling it up once will make the fight much easier with the Freeze Shot combination skill. Leveling Azumi up twice will make Azumi's Dia skill more effective at healing from Tsuchigumo's heavy hitting attacks.