Ibaraki Dōji is an oni from Heian-period Japanese legends, historically a key figure among the oni of Mount Ōoe. Though often depicted as subordinate to Shuten-dōji in folklore, she served as the primary commander leading the oni forces due to Shuten-dōji's disinterest in leadership. Her responsibilities included maintaining order among the oni and directing their guerilla warfare against humans. Her command ended during the "Oni Extermination of Mount Ōoe," when Shuten-dōji deliberately consumed the Providential Oni Poison, enabling Minamoto-no-Raikou and the Four Heavenly Kings to infiltrate and destroy the stronghold. Ibaraki Dōji alone survived. She later lost her arm to Watanabe-no-Tsuna in a confrontation at either Rashōmon or Ichijō-modoribashi, though she eventually reclaimed it. Her physical design evolves across ascensions. Initially, she appears as a small-statured female figure with light yellow hair, scarlet eyes, pointed ears, and prominent forehead horns that transition from black to red. Her attire includes a loosely worn floral-patterned yukata exposing her shoulders, blood-red limbs, and tribal-like tattoos. Later ascensions incorporate elements like fiery hair resembling wings, feather crowns, and shimenawa ropes, emphasizing her demonic nature. She wields a bone sword embodying curses and grudges. Personality-wise, Ibaraki Dōji balances her inherent oni nature—drawn to violence and human consumption—with a sense of order and duty instilled by her noble-born mother. She enforces rules among oni with harsh discipline, viewing humans primarily as prey rather than targets for wanton cruelty. Her deepest bond is with Shuten-dōji, cherished as a sworn sibling; her wish for the Holy Grail is solely to witness Shuten's genuine, carefree smile. This devotion conflicts with her resentment over Shuten's role in Mount Ōoe's downfall, leading her to conceal her affection. She harbors intense hatred toward the Minamoto clan, particularly Raikou and Sakata Kintoki. In *Fate/Grand Carnival*, her traits are exaggerated for comedic effect. She displays childlike excitement, notably when encountering the parody hero "Dharmapala Girl" ("Oni Cure"), reacting with starstruck enthusiasm. Her dynamic with Shuten-dōji includes playful denial of her excitability, such as during beach outings where Shuten teases her fidgety behavior, contrasting her typically fierce demeanor. Her combat abilities focus on high-damage Buster attacks and survival tools. Key skills include "Demonic Nature of Oni" (boosting party attack and her NP damage), "Violent Oni of Ōoe" (cleansing debuffs, healing allies, enhancing critical damage, and synergizing with Shuten-dōji for self-NP charging), and "Morph" (defense buffs). Her Noble Phantasm, "Great Grudge of Rashōmon," deals heavy single-target damage while stripping enemy buffs and applying defense down. Passive abilities include "Mad Enhancement" (boosting Buster performance) and a bond-based passive increasing party bond points. Theories regarding her legendary origins vary: she is said to have been born in Echigo (Sunagodzuka or Karuizawa) or Settsu (Amagasaki or Ibaraki). Stories describe her as a beautiful boy or a fanged infant causing maternal death or abandonment, eventually transforming into an oni after exposure to blood. These tales consistently culminate in her joining Shuten-dōji and targeting Kyoto.