Board Thread:General Discussion/@comment-174.49.208.85-20130613222339/@comment-25396835-20140815233142

What Sensei basically said is only one of these things is true:

-Sensei has a brother

-There is a secret ninja clan called kunoichi (thats a real thing: its a female ninja)

-There are some who still know old and forgotten styles of Card-Jitsu with Shadow being an example

-Ninjas and EPF are enemies (this one is definitely false)

-A time paradox was created at the Prehistoric Party so now there are penguins who knew of Card-Jitsu a very long time before Sensei

Its up to fan interpretation to decide which is true.