The world of anime has many character archetypes for heroes, villains and everything in between. These range from shonen action series to slice-of-life titles, such as the "big sister" role or the lovable doofus "himbo" archetype, with Son Goku being a prime example of the latter. Arguably, the most popular and distinct character archetype is the tsundere, a term even casual anime fans will know.
Tsunderes have been around for decades now, and such characters embody both tsun, (prickly hostility) and dere (warm affection and friendship). This archetype dates back to Neon Genesis Evangelion's Asuka Langley and likely even before her, and some fans want to know how they can spot a tsundere when they burst onto the scene in an anime or manga. These characters are diverse, but they do have some common traits.
Tsunderes Are Quick To Defensively Call People Stupid
A tsundere may act aggressive and tease other characters to look tough, but in reality, they are highly defensive since they don't want their amorous feelings exposed too easily. When other characters pry into this, the tsundere will get defensive and deny their feelings by calling the other party stupid or dense, often tailoring their language to the characters and situation at hand. Stereotypically, a tsundere might say "It's not like I like you... st-stupid!" Characters such as Chitoge Kirisaki from Nisekoi and Kyo Sohma from Fruits Basket are known to act like this.
A Tsundere May Have One Fang
This particular visual cue isn't unique to tsunderes, nor do all of them have the "one fang" visual gag. Still, there's enough overlap that if an anime viewer spots a confrontational character with one fang, there's a solid chance he or she is a tsundere or a playful bully. The one fang may appear while the tsundere is fussing at the lead and defensively calling them stupid, or if they are teasing or pestering in a more typical way. Erina Nakiri from Food Wars! has some tsundere traits, even if she didn't fully fall in love with anyone -- and is sometimes seen with a single fang. The same is true of Asuna Kagurazaka from Ken Akamatsu's hit manga series Mahou Sensei Negima!.
Tsunderes Have a Short Temper
A tsundere is likely to be inpatient, rash and reckless in some or all situations, regardless of whether romance is involved. This is part of the tsun half of their character, when they are standoffish, aggressive or even mean to other characters, and they are easily provoked. These tsunderes are especially short-tempered when the topic of their love interest comes up, and they get defensive.
Often, a tsundere will use violent visual gags to retaliate or avoid the topic, such as kicking the offending party high into the sky, clobbering them on the head with a club or even throwing them out a window. Kyo Sohma, for example, is quick to fight Yuki Sohma, while Taiga Aisaka of Toradora! fame is feared for her short temper and wooden sword.
Tsunderes Often Have Painfully Vulnerable Moments
Tsunderes are all about balance, with their genuine loving sides contrasting evenly with a fierce outer shell to create the complete tsundere package. But there is more than one way to compensate for a tsundere's violent visual gags and "you're so stupid!" accusations. These characters have their fair share of drama too, and may break down crying or make a dramatic confession of self-doubt or distress later on when the time is right.
Often, the tsundere character's inner pain or drama is the direct cause of their prickly exterior, and they will only admit this to their love interest or best friend. When these difficult moments are resolved with the love interest's help, the budding relationship might get a big boost.
Tsunderes Are Typically Stronger & More Assertive Than Their Love Interest
An exciting romantic relationship in anime is often based on strong contrasts between the two parties, such as size and height, combat prowess, assertiveness and even intelligence or species. Tsunderes are typically "stronger" than their love interest in one or more ways, such as having a bolder and more confident personality, or having superior martial arts or magical skills. They might also be an upperclassman in school or simply have more authority and influence than the love interest. That, combined with their almost bully-like personalities, makes the tsundere an apex predator of sorts, but not in a seriously harmful way.
Such power and authority can help contrast even more with the tsundere's inner vulnerabilities and soft side. Erina Nakiri in Food Wars!, for example, is a better and higher-ranked chef than protagonist Soma Yukihira, while Toradora!'s Taiga Aisaka is assertive and a formidable fighter while Ryuji Takasu is gentle and harmless.