The Card-Jitsu Series is a group of Mini Games with the prefix "Card-Jitsu". Card-Jitsu can be played in the Dojo, and Card-Jitsu Fire, Card-Jitsu Water and Card-Jitsu Snow can be played at their own dojos respectively. A furniture item called the Card-Jitsu Mat was introduced in December 2011, and it can be used to play Card-Jitsu in a Penguin's igloo.
Each Card-Jitsu game has its own prize, the Black Belt and the Ninja Mask for beating Sensei in Card-Jitsu, the Fire Ninja outfit for beating Sensei in Card-Jitsu Fire, the Water Ninja outfit for beating Sensei in Card-Jitsu Water, and the Snow Ninja outfit for beating Sensei in Card-Jitsu Snow.
All Card-Jitsu games are multiplayer games and can support a maximum of 4 players. (Card-Jitsu can support 2, while Snow can support 3 without Sensei). To battle with Sensei or to battle Tusk (Snow), you need to acquire the clothing you need (Belts for Card-Jitsu, Fire Ninja, Water Ninja, and Snow Ninja clothes of CJ Fire, CJ Water and CJ Snow respectively). To earn them, you'll have to play against other penguins and win matches. You will also get a "Starter Deck" when you first play a Card-Jitsu game.
From September 2009 to May 2013, Non-Members could not play any of the Card-Jitsu spin-offs. However, during the Card-Jitsu Party 2011, they were able to play them temporarily, and as of the Card-Jitsu Party 2013, all players can play all variations of Card-Jitsu.
If a penguin defeats Sensei in Card-Jitsu, they become a Ninja. If they beat Fire Sensei, they become a Fire Ninja, if they beat Water Sensei, they become a Water Ninja, and if they beat Tusk, they become a Snow Ninja. Each ninja has its own weakness and strength. They also have their own uniform and their own special dance. If more than 5 fire, water, or snow ninjas do their special dance, the sky will change to the respective element.