Yoroshiku Master by Sakura Tsukuba
I picked this story with the holiday spirit in mind! It is by a manga-ka that I really enjoy and have talked about on occasion. She writes really spunky females and good-hearted romantic leads. This series is ongoing and she writes a little of it now and again. In this story, Sagara has a chance meeting with a guy named Kaito who all of a sudden transforms into a reindeer?! Not only that, he informs her that she is one of many santas. Funny, sweet, fluff ensues as Sagara gets to know Kaito (and his hilarious family) and as they prepare for the most important night of the year, Christmas Eve! There is no major drama here just light-hearted romance that is a perfect match for the season!
Liar Game by Shinobu Kaitani
Liar Game starts with Nao Kanzaki dropping of a 100 yen bill that she finds to the police to show us that she is stupidly honest. So when she gets involved in a game about being a great con-artist she is without a doubt up a creek without a paddle. She comes home to a package that reveals she has been chosen to take part in the Liar Game tournament. The briefcase contains 100 million yen and a set of rules. When the round is over she must give back the 100 million yen. Any money she takes from other players is hers to keep. Any money she loses she must pay back. Soon enough she winds up loosing all her money to a fellow player. Out of despair she teams up with a brilliant con-artist named Shinichi Akiyama,who has recently been released from prison. The Liar Game tournament is much bigger than they might have guessed. Also learn the organization behind the tournament seems to have some greater but unknown designs behind their games.
Whenever Liar Game comes up in conversation it is almost always compared to Death Note. This is not an unfair comparison since the core appeal to both series is the psychological games of cat and mouse. In each stage of the tournament, it is Nao and Shinichi trying to figure out the underlying strategy needed to win the game while deducing their opponents strategy. Shinobu Kaitani has been good at building up the tension until the end of each round of the game. There was also a 11 episode live action version made and was rather well received.
Reverse Thieves 
I think you meant Liar Game.
Wow, that was embarrassing! Thanks!