I have Manky card in Japaneses but is it rare?
If you bought it second hand then it's kind of rare because its a regular Japanese card outside of Japan. Thats all, nothing special. If you bought it in a English pack and you got a Japanese Mankey card that is rather strange.
On the other hand the first card at the top is an expantion on the last card. So I guess that makes it kind of rare ;)