Vanir

One of the generals of the Demon King's army. A rare friend of Wiz. The protagonist of the spin-off "Consulting with the Masked Devil!" A Duke of Hell, commonly known as the "All-Seeing Devil." As a demon, he feeds on the negative emotions emitted by humans. His laugh is "Fuhahahaha," and he refers to himself as "I." The mask is his true body, and in the novel's illustrations, he is depicted as a large man wearing a black tuxedo and a white tie.

As the "All-Seeing Devil," he has a unique way of speaking that sees through others' actions and thoughts. Like Wiz, he cooperates only to maintain the barrier of the Demon King's castle and has wanted to quit the Demon King's army for a long time. He has a cat-and-dog relationship with Aqua, both racially and temperamentally, and they fight every time they meet.

He frequently uses a technique called "Vanir-style Death Ray." Although it has never been used against people in the series (Aqua, being a goddess, is not included), the aftermath often hits Wiz and Darkness. As the name suggests, the death ray is supposedly lethal, but Wiz and Darkness have survived it (it's understandable for Wiz, who is a lich, but it's unclear why Darkness can withstand it). He also possesses an eye beam, but using it scorches his own eyes, so he has not used it yet. He also exhibits bizarre behaviors typical of creatures in this world, such as suddenly shedding his skin or growing a body from his mask.

He often sets up business deals with Kazuma. By purchasing the intellectual property rights to lighters, kotatsu, and other items known to Kazuma, he mass-produces Japanese products to realize his long-held dream and earn operating funds. He does not intend to harm humans, and the negative emotions he enjoys are not fear or despair but the disappointment felt when expectations are betrayed, so he rather enjoys teasing humans without hurting them too much. However, he claims to be "Vanir-san, who might be stronger than the Demon King," and indeed, his abilities are high.

When the corrupt lord Alderp employed a demon (Maxwell) to commit evil deeds, Vanir not only exposed him in front of the public but also had Maxwell, whose contract he terminated, take him to hell to pay the price until his death, showing a side of him as a demon that is hard to imagine from his usual self.

In the dungeon, he confronts Kazuma and the others, takes over Darkness's body, and defeats many adventurers in a weakened state. He also battles with Kazuma, but is ultimately defeated when his true body, the mask, is destroyed. It seemed he had died, but in reality, he only lost one life (afterward, the character "II" appears on his mask's forehead), and he revives. Having been defeated once, he loses his position as a general of the Demon King's army and subsequently works part-time at the store managed by Wiz.

In the spin-off, he occasionally opens a consultation desk at the guild. He also regularly chases away crows gathering at the local garbage dump, becoming so familiar to the neighborhood housewives that they call him "Crow Slayer Vanir."

Ranked 10th in the official Kadokawa Sneaker Bunko site TV anime character popularity poll.