Usogui

"You... are a liar."

- Bak's quote after winning a game

Usogui is a psychology- and gambling- based manga by Toshio Sako.

There are gamblers out there who even bet their lives as ante. But to secure the integrity of these life-threatening gambles, a violent and powerful organization by the name of “Kagerou” referees these games as a neutral party. Follow Bak Madarame a.k.a. Usogui (The Lie Eater) as he gambles against maniacal opponents at games – such as Escape the Abandoned Building, Old Maid, and Hangman – to ultimately “out-gamble” and control the neutral organization of Kagerou itself.

Usogui provides examples of:

 * Badass Bak Madarame is a very good Chessmaster, but his pawn Marco's first appearance has him killing three Mooks in the space of a single minute. They were on three different floors
 * Batman Gambit Bak uses his opponents' personalities against them. Q- Taro found this out the hard way when Bak recruited Marco during his battle with him. He used Q-Taro's belief that Marco was dead to lure him out and attack him with Marco.
 * Heel Face Turn Marco joined Bak's side after asking Bak who he was. Bak's response: "That's something you must decide for yourself."
 * Serious Business Bak treats slots as such. But his entire life has been about life-or-death gambling, so...
 * Xanatos Gambit All of Bak's strategies are these. If an opponent calls his bluff, he reveals that it wasn't a bluff and wins any way. He duped a fraudulent loan agency into giving him three million yen (30,000 dollars) by calling ahead with the numbers for a winning horse-race ticket and then giving the loan sharks the ticket for collateral. The ticket was fake.
 * Xanatos Roulette Some of Bak's plans seem to be this. But he actually does try to learn everything about a target, down to their personalities, forces, and supplies they would have hidden in their building. Yes, he even plays roulette this way.