yanderu

Yanderu is a Japanese expression that describes being unwell, typically in a mental or emotional sense, though it can also refer to physical illness in casual speech. The phrase derives from the verb 病む (yamu), meaning to suffer from illness. The progressive form 病んでいる (yandeiru) indicates an ongoing condition, and in everyday use it is often shortened to yanderu.

In common usage, yanderu signals a subjective state of distress, exhaustion, or moodiness rather than a formal medical diagnosis. It is frequently employed in informal conversation, social media, and online communities to convey how someone feels on a given day. The nuance can range from light, self-deprecating humor to expressions of genuine emotional strain, depending on context and tone. Because it describes personal feelings, it is not a clinical term and should be used with sensitivity to avoid stigmatizing mental health issues.

Yanderu is distinct from yandere (ヤンデレ), a widely known character trope describing someone who becomes violently possessive or psychotically attached in a romantic context. While the two terms share a root related to illness or instability, yanderu refers to real or perceived emotional states, whereas yandere denotes a fictional persona.

Related terms include 病む, 病んでいる, うつ (depression), and measures of mental health and well-being.