King = Ousama
+
Cat = Neko
If you were to combine the two and say "nekousama" in context, the pun may not be lost to a surprising majority of Japanese people.
demon blade in Japanese is akuma no tsubasa
You may say 'oni no neko,' written: 鬼の猫
There are manyways for example a kitsune is a fox demon, however the most common one reffering to demons in geral is youkai. In Japanese the words cat demon is Neko youkai.
Ookami means wolf in Japanese and yasha means demon in Japanese. Ookamiyasha means wolf demon in Japanese and yasha ookami means demon wolf in Japanese.
'Beautiful demon' would translate to 美しい鬼 (utsukushii oni) in Japanese.
猫の悪魔 Neko no akuma
black c*nt me the black c*nt in asia
'Koneko' is kitten in Japanese.I don't know about kitty, but i know that cat is neko.  
demon blade in Japanese is akuma no tsubasa
You may say 'oni no neko,' written: 鬼の猫
There are manyways for example a kitsune is a fox demon, however the most common one reffering to demons in geral is youkai. In Japanese the words cat demon is Neko youkai.
ma o
The Japanese word for 'Demon World' is 鬼の世界.
It's a general Japanese term for demon lord, powerfull demon, or large demon.
Akuma. it means devil or demon.
Ookami means wolf in Japanese and yasha means demon in Japanese. Ookamiyasha means wolf demon in Japanese and yasha ookami means demon wolf in Japanese.
Demon = "Oni" or "Youkai" + Blade = "Katana" or "Ken"