A sound effect used for imitating a Cat's cry. The Japanese equivalent of "meow".
This tag includes variations such as "nya", "nyaa", etc. In Japanese, it can be written as: にゃん, にゃ, にゃー, にゃあ, ニャン, ニャ, ニャー, ニャア, and probably a few other variations.
Often accompanied by a Paw Pose or other cat-like mannerisms.