Yu-Gi-Oh

Yu-Gi-Oh! is a Japanese cartoon (Anime) that began in Japan in 1998. It's about a high school freshman named Yugi whose grandpa gives him an ancient Egyptian puzzle that no one has been able to solve. Somehow, Yugi solves the puzzle and releases a mysterious, dark power that gives Yugi the ability to unlock an alter-ego called Yami-Yugi. Now every time Yugi duels someone in Duel Monsters (a card game similar to Pokemon and Magic the Gathering) he is transformed into Yami-Yugi, a more confident and courageous version of himself. What comes after is an ever twisting plot of dark powers, close duels, evil lowlives, and soul stealing.