'Tsundere' is a term from Japanese anime and manga culture, describing a personality or behavior that alternates between a cold, distant attitude and hidden warmth or affection. This duality of 'tsun' (aloofness) and 'dere' (affection) creates a unique charm, and the term has grown popular as a character trope.

The 'tsun' side is a cold or aloof attitude, often shown when someone has trouble expressing their true feelings directly. Underneath, however, they feel affection or fondness that occasionally surfaces as 'dere,' showing sweetness and kindness.

The 'dere' side is the affectionate, kind-hearted expression that creates an endearing contrast with the 'tsun' moments, adding depth to the character.

Since the 2000s, 'tsundere' has gained popularity among fans for its 'gap appeal' and has even come to describe real-life personalities. It has become a way to capture both the diversity and relatable complexity of characters, as well as human interactions.

The personality traits of a tsundere can be explained by a few psychological theories.

First, the 'ambivalent attachment style' in attachment theory is similar to tsundere behavior. People with this style often desire affection but fear rejection, leading them to hold back or keep their distance.

A tsundere's coldness can also relate to a defense mechanism called 'reaction formation,' where they suppress their true feelings and act in the opposite way to feel secure.

Finally, anxiety around self-expression is another common trait. The fear of revealing one's true emotions may appear as a 'tsun' or cold attitude, serving as a protective response in relationships.