|Master of Hell|
|Anime Debut||The Possessed Girl|
|Japanese V.A||Hidekatsu Shibata|
|English V.A||John Swasey|
Usually, the Master of Hell appears as an oddly-colored spider with three eyes upon its abdomen. Another one of its forms was shown in the beginning of Two Mirrors, where it appears as a giant jellyfish with four glowing shapes on top of its head. Three of the slits can reveal themselves to be eyes. It speaks with a deep voice.
Being the Master of Hell, it rightly possesses an evil personality. It is shown to be cruel and manipulative, as shown when it forces Ai Enma to become the Hell Girl by holding her parents' souls hostage. Occasionally, it visits Ai in his spider form to spy on her and ensure Ai does her job objectively. Despite that, it does not hesitate to force her into situations where her temperament is tested. It does, however, keep its promises, as shown when it releases Ai's parents after she completes her job.
The Spider, identified by Wanyuudou as the God of Hell, is the one that punished Ai with the burden of being the Hell Girl. After an enraged Ai had burnt down her village, killing most of its residents, the Spider took the souls of her loved ones (her parents) hostage, and threatened to make them wander through darkness for eternity unless Ai performs the tasks it gives her. The Spider is ever watchful of Ai's actions, always looking for a chance to spot her acting on impulse, which is apparently against the rules of the Hell Girl. It would seem that The Spider even deliberately makes her face situations reminiscent of her past, in an effort to bring about the same. It also seems to try to provoke Yuzuki during her brief time as Hell Girl, and succeeds in this.
Although it is called 'The Spider', this is only the shape it takes on in the mortal realm and in the Eternal Twilight, or to communicate. Near the end of both Two Mirrors and Three Vessels, it is revealed that he inhabited the body of Kikuri. It was not clarified for how long the master of hell has been inhabiting Kikuri, and how much of Kikuri's behavior is actually due to him. In Hell, The Spider appears as a sun-like object composed of four lines. When it brings Ai into Hell to show her the souls of her parents, three of the lines swell and turn into eyes so that it resembles its lower body in its spider form.
Season 4 to be added.
Hell Ferrying: The Spider is shown to be able to row the boat across the Sanzu River. It's also capable of drawing people into Hell, which is how it traps Ai and her parents.
Teleportation: The spider occasionally appears in the eternal twilight to watch Ai and her assistants. Additionally, when it recruited Ai to become the Hell Girl, it suddenly appeared in front of her.
Invulnerability: At one point Yamawaro fires some sort of blast at The Spider and manages to knock it back, but it isn't damaged, merely surprised.
Shield: Although Yuzuki tried to attack the Spider, it projected a shield which deflected the attack.
Webbing: The Spider uses webs to trap Ai and later Yuzuki when they try to rebel against it. Although Ai seems to be able to break these webs, Yuzuki doesn't seem to have enough power to do so.