Despite its literal meaning as “cat ears”, Nekomimi 猫耳 is commonly used by otaku as a slang to refer to anime/manga characters that are imbued with feline characteristics. The other literal term nekomusume (猫娘) is not used that often anymore because nekomimi can be applied to male characters (e.g. LOVELESS or Lamento).
In general, the obsession with animal ears is called Kemonomimi 獣耳, and while catgirls are the most prolific, there are also bunnygirls, foxgirls, and dog girls. Apart from the emphasis on the pair of furry ears, nekomimi characters exhibit other unique feline characteristics as well such as:
- having a tail, and will become jumpy if you grab his/her tail
- clasping of both hands to make them seem like the paws of a cat
- frequently ending sentences with the word “Nya(n)”
- sometimes enjoy licking herself
Of course, the nekomimi is a popular moe element just like the “Zettai Ryouiki 絶対領域” or the “Shimapan 縞パン“. Hence it is not uncommon to see it being mixed with other elements such as sukumizu (school swimsuit) or meganekko (girls with glasses).
My favorite nekomimi character to date has gotta be Tsubasa Hanekawa (羽川 翼), who was possessed by a bakeneko in the anime series Bakemonogatari.