Manga block

（/TДT)/
Can someone tell me what is the name of this manga??i have read it before..there's a guy--he's someone like L of deathnote..and then a short black haired girl. It's about a game,more like a gamble which you just have to win. They have to deceive one another. The guy was totally clever. The girl was a bit timid type but she's learning to deceive their opponent.augggrr..i know it's quite a bit hard to tell with my description. But plss..can anyone help..there was a poker on one of the challenge