It's a manga currently running in weekly Shouen Jump alongside the other big three, its recently hit 104 chapters and i tell ya, its hit the ground running in terms of quality and story development. It's about a japanese high student who stumbles across an urban legend, that of the Game Psyren and its creator the being known only as Nemesis Q. After gaining a red calling card that makes him part of the game, he and a girl he knows are thrust into the World of Psyren and are forced to battle for their lives, meeting old friends and new friends on the way. Of course nothing is what it seems and the world of Psyren itself is strangely familiar to the characters. There's equal revelations and questions and it never lets up with the fights. Plus unlike other Shouen shows, the characters tend to win more fights by using their head then just rushing in and discovering some 'hidden power' (i'm looking at you Dragonball)