猫の悪魔 Neko no akuma
demon blade in Japanese is akuma no tsubasa
You may say 'oni no neko,' written: 鬼の猫
ma o
ダークデーモン
King = Ousama+Cat = NekoIf you were to combine the two and say "nekousama" in context, the pun may not be lost to a surprising majority of Japanese people.
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
Hi no akuma
aoi akuma
Furasshu no akuma
'Beautiful demon' would translate to 美しい鬼 (utsukushii oni) in Japanese.