Look at this reply.
Sorry for the delay in this response.
We do not currently have a Ninja costume available in Club Penguin, but that
does not mean that there never will be one.
There are a lot of very creative penguins out there in Club Penguin who use
what ever items they have collected to create their own Ninja style, so just use
your imagination and have fun with it and you could be what ever you want.
If you have any further questions please reply and I would be happy to help.
Club Penguin Support
That means that sometime there going to come out with ninjas in club penguin!