You know the catgirls that proliferate manga, anime and video games? (These are typically girls with cat-like features, such as cat ears and tails. Look at Zoey/Ichigo from Mew Mew Power for an example.) Or maybe you’ve seen catgirls on the streets of Japanese cities. (These are typically schoolgirls who, for the sake of fashion, wear headbands with fluffy cat ears on them – not quite the same animal as the ones in the comics.)
One thing about the whole phenomenon has started to annoy me, and that’s the name that anime geeks have given them. They call them “neko mimi” and write it “猫耳”. Now these two characters mean “cat” and “ear” respectively, and the native Japanese readings (kun-yomi) are “neko” and “mimi”.
But if you see two ideographic (kanji) characters jammed together like that, you don’t use the native Japanese readings. You use the Chinese-derived readings (on-yomi). For example, “少女” (young girl) is read always as “shou jo” and never as “suko onna”. On the other hand, “少し女” (notice the conjunction) is read as “suko shi onna”.
Likewise, “猫耳” should be read as “byou ji” (although no-one would ever say that), and “猫の耳” should be read as “neko no mimi” (note the conjunction).
Now there are other cases where people want to use the native Japanese reading for several characters in a row with no conjunctions, such as the company Kuro Neko Yamato (roughly Yamato the Black Cat). But they make the desired pronunciation obvious by writing their name in phonetics (katakana), as “クロネコヤマト” rather than the ideographics “黒猫大和” (which should be pronounced “ji byou dai wa” or maybe “ji byou yamato”).
“Neko mimi” should be written in phonetics (i.e. as “ネコミミ”), or else catgirls should be called “byou ji”!