TV-Series
Description
Rangui, known as The Black Widow, serves as a primary antagonist alongside Omodaka. She wields sorcery through paper seals for magical attacks and transforms into a large spider-like monster resembling the Jorōgumo.

In the anime, Rangui draws imperial soldiers to drain their life force. She traps Lieutenant General Takatoshi Hanadate and deceased soldiers in a giant web during a Ministry of Spirit Affairs investigation. After a confrontation with Zakuro leaves her scarred, she reveals knowledge of Zakuro's mother, Tsukuhane, and escapes. Later, she orchestrates the capture of Kei Agemaki and Susukihotaru to lure Zakuro and Riken Yoshinokazura. Rangui displays a manipulative relationship with subordinates Byakuroku and Daidai, healing Byakuroku while showing conditional tolerance for Daidai. Learning of Omodaka's plan for Zakuro to bear his child triggers jealous rage, driving Rangui to attempt Zakuro's murder. Her schemes escalate as she manipulates Daidai into burning a village before betraying and killing her, provoking Byakuroku's failed retaliation. In the final battle, Rangui attacks an unconscious Zakuro and traps both Zakuro and Kei, engaging multiple opponents including Omodaka. Zakuro's awakened power, triggered by Kei's love confession, ultimately destroys her.

The manga depicts similar initial events but diverges after Zakuro's abduction. Rangui confronts Ganryu Hanakiri and the twins Bonbori and Hozuki again, facing defeat. Later, she ambushes the protagonists in a tunnel with a spider web, restraining Byakuroku and declaring her intent to kill and consume Omodaka. When Byakuroku intervenes to save Omodaka, Rangui fatally wounds her. Omodaka then impales Rangui with a sword, ignoring her hallucination of Tsukuhane, and reverts her to an ordinary spider.

Her actions stem from a vendetta against humans and obsessive jealousy toward Omodaka. She exploits vulnerabilities, manipulating Daidai's loyalty and Byakuroku's dependence. Her knowledge of Tsukuhane and frequent taunts directed at Zakuro suggest a personal connection to Zakuro's past, though its exact nature remains undisclosed.