Relax, it's a cat 100%. Manx cats have longer hind legs than many other breeds of cat, giving them a funny appearance anyway. Couple that with the fact that the gene that causes taillessness in Manx cats is actually similar to that that results in Spina Bifida. Manx cats with stub tails are less prone to it - Manx cats with no tail at all are sometimes born with major spinal problems, and other unpleasant birth defects. To breed Manx cats, you must breed a Manx to a non-Manx as breeding Manx with Manx results in a greater expression of the lethal gene, and the kittens don't often survive.
/Had Manx cats, love them to bits.
Edit; These cats could also be Japanese Bobtails, a similar breed to the Manx, if the language is any indication of the origin of the cat in question.
(, Mon 26 Jan 2009, 7:31, Reply)