"Am I a mouse, a dog, or a bear?" Nezu poses this rhetorical question when he first introduces himself. The Wikia article about him says that he seems to have characteristics from several different animals. But I object to this. In my opinion, Nezu is clearly some variety of mustelid!

But what is a mustelid? Mustelids are a family of carnivorous mammals, including weasels, martens, minks, badgers and otters. There are 57 different species, including the otters. With that many species, there's quite a different range of varieties, but overall they are small with short legs, short roundish ears with and thick fur. Many species have long skinny tails and sharp teeth. Nezu doesn't match up entirely with one and only one species of mustelid, but there are still many similarities between him and the mustelid family in general. Not to mention that with the BNHA universe quite literally being a post apocalyptic one, there could have been enough evolutionary pressure to cause changes among mustelids in Japan. Then there's the possibility that he's an albino of whatever kind of variety animal he is and wears contacts to cover the redness of his eyes. Or his white fur could be a side effect of his intelligence quirk. There are multiple explanations for the small ways he's different from some species of mustelid. But he doesn't fit well with the possibilities that are handed to us. Nezu is far too big for a mouse, but the largest species of mustelid can grow over 5 feet long. He could be a dog, but his body and face are far too rodent-like. In the fan wikia he's even listed as looking like a humanoid mink. I could rest my case there, but I won't. And there's no way he's a bear with a tail like that. But look! His triangular head shape, the shape of his ears match up well with different kinds of mustelids. Look at these pictures!




An American Mink




A stoat making a silly face.

And when viewed through the lens of his being a mustelid, his personality makes more sense. Bears can be vicious, but mice and dogs aren't usually. Dogs have to be taught to be vicious, often abused. Nezu is extremely polite and optimistic, hoping that through teaching he can steer would be villains into less destructive lives, although he acknowledges this as naive. He is a good friend to Toshinori and cares deeply for his students. The darker side to his personality comes from a period of time when he was experimented on by humans. (Side note: I think that this could account for the greatest physical discrepancy between him and most mustelids. Mustelids have five digits on their fore-paws, while Nezu has four. But if you were experimenting on a creature with a high level human-like intelligence, what better way to prevent escape and dehumanize him than removing his thumbs?) He holds a grudge against humans, and feels a sadistic joy in toying with them on occasion. Mustelids have solitary natures, and are often cooed over for their cute, pointy faces and sleek bodies. A few species are noted for their viciousness however. As an American BNHA fan, I can't help but think of how when it was all the rage a couple of decades ago for anti-fur farm activist groups to break into fur farms and release all the minks, they devastated the surrounding environment. In general they are territorial and fight fiercely with possible invaders. Farmers often dislike them because they are "greedy" and can often carry off prey that's much larger than themselves. They often dive down the burrows of their prey and chase them, dragging them out into the light. This hidden, quick ferocity reminds me very much of Nezu.

But being an American fan, and BNHA being fiction, I can't just rely on biology to make my case. I have to go poking into Japanese mythology and folklore. The member of the mustelid family that has the greatest presence in Japanese mythology and folklore is the Japanese marten.




A Japanese Marten

The coloration isn't quite right, but there are a number of reasons why he could have a different color scheme. (Evolution, his quirk causing a mutation, albinism...) Interestingly enough, the marten is supposed to be a better shapeshifter than either the kitsune or the tanuki, a saying being that "the fox has seven disguises, the tanuki eight, and the marten nine." Martens are thought to be omens of bad luck in some areas, or the disguised souls of those who died in avalanches that bring pain and suffering. One source says that if they live to an advanced age they can become yokai, and gain the ability to set fires. If a bunch of martens climb on top of one another, they are supposedly preparing to set fire to people's homes. The thunder spirits of Japan, the Raiju, are often depicted as being some variety of bizarre weasel. Those who have seen the raiju say that they are calm and pleasant beasts until it begins to storm, and then they become shrieking, aggressive beasts that attack everything within reach. Whether or not Horikoshi had this in mind when he designed Nezu, the raiju ring a bell, don't they? When Nezu is acting as Kaminari and Mina's examiner, purple storm clouds show up behind him in when he starts to laugh while operating the wrecking ball. And Nezu does a kind of shapeshifting, appearing harmless but have a sharp, strategic, and sometimes sadistic intelligence.

Mustelids are clever and adaptable, with species across the world. They're incredible cuteness belies their sharp intelligence and strength. They are omnivorous predators, and should not be underestimated. Mice, dogs and bears are all well and good, but people tend to either underestimate them, seeing them as cute little prey animals, or loyal pets, or strong but not very smart. Nezu is none of these things. He's a powerful ally, and I think his being a mustelid only enhances his complex character. People tend to reduce him down to his appearance, position as the principal, his strategy or sadism but these are all facets. Of course, there's one more small, curious little detail. Many different kinds of mustelids have musk glands that they use to spray their enemies with, deterring them with a foul smelling liquid. I doubt we'll ever see this come up in BNHA, but I think it's an interesting little detail!