Spider Demon (Father) (蜘蛛鬼「父」 Kumo oni: Chichi) was a member of the Spider Family.
Physically, Father was the largest of his "family", possessing great height and a powerfully built physique. His skin was dark brown with the same red, dot-like design extending from his shoulders reaching down to his arms as other members of his family. Like his "wife" and "children," Father also had pale white hair reminiscent of Rui, though his' was much longer, reaching down across his shoulders. His most unique trait was his monstrous face; unlike his "family's" more humanoid appearance, his face was identical to that of a true spider, with several eyes and large pincers for a mouth.
When he moulted, he gained green skin with blade-like protrusions sticking out of his arms and legs. He lost all his hair and obtained sharper teeth and more pronounced mandibles. He also gained five spikes going upwards on his forehead. Finally, one of the most notable changes was that the number of his eyes doubled from nine, to eighteen.
Father was animalistic, aggressive and extremely bloodthirsty. He was shown to be very devoted to his "family", as when he battled Tanjiro Kamado and Inosuke Hashibira, he repeatedly told them to stay away from his family while attempting to kill the duo. He served as the main protector and was seen being on the lookout for the Demon Slayers when they came to Mount Natagumo. However, he was also shown to be very abusive towards his "wife," having repeatedly slashed and physically abused her in the past without even stating his reasons for doing so due to her being weaker than to what they originally expected of her.
Mount Natagumo Arc After Daughter called for him, Father landed in front of Tanjiro and Inosuke. He angrily yelled them to get away from his family, before attacking them with a fierce punch. He easily blocked Tanjiro's Water Breathing, Second Form: Water Wheel technique, attempting to counter with another punch, only to be thwarted by Inosuke's twin swords pinning his arms down. He threw the two Demon Slayers off of him, immediately charging and attacking Tanjiro while repeating his earlier demand. Inosuke attempted to attack him from behind, only to be immediately punched. The Spider Demon continued his assault on the boar-headed Demon Hunter, only to be pinned by a tree that Tanjiro had cut. He quickly recovered from this and eventually used the tree to fling his assailant into the distance. Later, while Inosuke contemplated his next move, Father attacks him, breaking the tree he was leaning against. Surprised by his opponent's quick retreat into attack, the paternal demon blocks the strike, but has his forearm severed when Inosuke uses both of his blades. Briefly examining his stump, Father then retreated, climbing up a tree, before shedding his skin and assuming a new form. He then descended the tree, ready to resume the battle. Readying another punch while simultaneously throttling his opponent, Father once again repeated his earlier demand, only to be stabbed in the throat by his resilient adversary. Unfazed, he tightened his grip on the youth's head, only to have his forearm severed once more, this time by the arrival of Giyu Tomioka. Howling in pain, Father immediately regrows it, charging at Giyu. His offense and existence are soon erased as Giyu strikes him with the Water Breathing, Fourth Form: Striking Tide, severing his neck and cutting him into multiple pieces. Overall Abilities: For a demon who isn't a member of the Twelve Kizuki, Father has shown himself to be quite a powerful demon. He was easily the second strongest member of the Spider Family and was able to take the combined might of Tanjiro Kamado and Inosuke Hashibira without fail. Father was likely seen by his "family" to be the main guardian and protector, due to his role and strength; unlike the other members who mainly hid from the Demon Slayers, he was seen actively hunting on Mount Natagumo to find intruders. Despite his above-average strength for a non-Kizuki demon, he still proved no match for the Water Hashira, Giyu Tomioka. Enhanced Strength: As expected for his immense size, Father possesses great physical strength. He was able to punch boulders to pieces, grab a tree trunk and swing it with great speed, fling Tanjiro away over a great distance and punch Inosuke with such force, he slammed into several trees before stopping. Enhanced Durability: Notably, Father displayed physical durability that is uncommon in most demons, likely due to Muzan's blood in him provided by Rui and his size. Tanjiro and Inosuke found it difficult to slash through his arms and he was able to shrug off multiple attacks. Metamorphosis: Father possessed the ability to shed his outer skin in order to transform into a more powerful form with increased physical power and regenerative abilities, making him even stronger and durable than in his original form.
Towering over his astounded opponent, Father punched him with great force, following through almost immediately with another blow, which Inosuke only avoided by jumping into the air. Inosuke attempted to sever the Spider Demon's neck with his Beast Breathing, Third Fang: Devour, only for his blades to shatter upon contact. Father immediately countered, sending his adversary hurtling into yet another tree before picking up the Demon Slayer up by the head.Abilities