XD centers on Dark Pokemon, Pokemon who've had their hearts sealed away and now use Dark Skills to attack you and your Pokemon friends. You play as a nameless main character who adventures with his little sister, Mana. Your quest is to free the Dark Pokemon from their misguided trainers and open their hearts back up. To do this, you'll make use of an eye piece called the Aura Searcher, which identifies Dark Pokemon by their characteristic purple glow, and your Snatch Machine, which plucks the Dark Pokemon from battle. XD features a full RPG-style quest, taking you to various towns and locations. You'll meet a number of human characters on your travels. Nintendo seems to be preparing a more fleshed out quest this time around.