After moving into Wiz's shop to help her out, he became a self-proclaimed "model citizen of Axel". He routinely meets with other inhabitants of the city to do idle gossip, enforces trash dumping rules, is a part of the board of merchants, and has been dubbed "Crow Slayer Vanir" for his efforts in driving the birds away from dumpsters around the town.
Vanir appears as a gentleman with slicked back hair, wearing a black and white mask with a small star design placed under each eye hole. Later, the roman numeral for 2 (II) replaces the star (signifying he had lost his life once). With this second mask, he states he is now reborn, now as "Vanir MK-2".
He wears a black suit with white gloves which is the typical attire for the Dukes of Hell. However, his physical body in the mortal realm is only the mask and the current human body is just an add-on. Vanir's real body is hidden away in Hell and he can quickly resurrect into another mask if he is "killed."
It is revealed in his spin-off that he has a stunningly handsome face underneath the mask, enough to make the Adventurer's guild receptionist Luna to fall in love with him when Vanir showed his face to her.
Vanir acts rather egotistically and is driven by self interest. He has a tendency to shamelessly boast about himself, but also has the extraordinary powers to back up many of them. While he claims that might is right, he helps the weaker on numerous occasions in an altruistic manner, offering useful advice or giving them a way to overcome tough challenges.
He always keeps the promises he made, does not use his foresight power to swindle money, and has never killed humans. However, while he has many noble attributes, it would be a big mistake to believe that he is an ally of justice. He is an arch devil that feasts on humans' shame and disappointment. So he has no problem using his power of foresight to detect and blurt out other people's embarrassing secrets. He also loves to pull mean pranks on humans and feast on their negative emotions. Despite this, Vanir has no taste for emotions like despair, viewing it as a waste of a good food source; he prefers shame and disappointment.
He is rather business savvy and treats his friends fairly. He can have great business success with his own shop, but chooses to stick by his friend and helps in Wiz's Shop. However, he does punish Wiz with his "Vanir-style Death Ray" for some of her unbelievably bad business deals. He also makes several deals with Kazuma to market his replicas of the items from modern Japan. While the deals benefit Vanir financially and further one of his hidden plans, he does make sure Kazuma is fairly compensated.
Vanir is an immensely powerful character, so much so that speculation among the Demon King's army has led to rumors of him being stronger than the Demon King himself and powerful enough to take part in a war against the gods in a primordial era long before the events of the story. Claire and Rain, Iris' bodyguards, also expressed surprise, and subsequently fear, when Vanir dealt with a good deal of armed guards with a mere wave of his arm, further cementing his reputation as being a devil to be reckoned with.
Divination: He is shown to be quite good at divination, while it is taken with much skepticism and he usually only reveals enough to tip events to his favor, his predictions are quite accurate, predicting that Aqua would arrive in Axel and that Darkness would face troubles before she was almost forced to marry to Alderp. This power seems to have some limits on it however, as he mentions that if he uses it for his own gain too much, the events will be manipulated to backfire on him.
Mask: Vanir's true body is a black and white mask, partially composed of the bones from magic dragons. If Vanir attaches the mask to someone's face, he can subject them to intense pain, and if their willpower wavers enough, he gains control of their body. Even if the mask itself is destroyed, Vanir has proven capable of surviving, resurfacing with a new mask labeled with a number to signify which life he is currently using.
Doll Creation: Vanir uses magic to create false bodies made from earth, one of which constantly wears his mask. He suffers no damage when a false body is targeted, and they can quickly be reformed from the earth if destroyed. He can split a false body to create a long-lasting empty shell of himself. He can also create miniature Vanir dolls as weapons. They seek out moving creatures, then latch onto them and detonate themselves. Kazuma rates their explosions as powerful, but adds that an adventurer in armor shouldn't die easily from them.
Foresight: Vanir has the power to read minds. Though this is typically used to expose embarrassing secrets, he has also used it to gain critical knowledge on opponents, and to make highly accurate prophecies.
Vanir-style Death Ray: Vanir shoots a luminous beam of incineration from his hand towards the target, causing them to collapse in pain if not being outright incinerated. This was used on Wiz several times as a comedic act for her insanely terrible business decisions. The Vanir-style Death Ray is a fearsome ability, with only extremely high level or durable characters such as Wiz and Darkness being able to survive it.
Immense strength: Was able to wrestle with a dragon which was as big as a storage room
- While it may have just been in jest, in volume 15 he claimed to be stronger than the Demon King in a very matter-of-fact manner.
- Although he takes the form of man, Vanir admits that biologically, like all other demons and angels, he is originally sexless.