Liar Game by Shinobu Kaitani
This is the one that got me hooked on psychological thrillers and seinen from the beginning- and it’s still one of my favourites. Kakegurui pales in comparison to the complex games and ingenious twists and strategies that Liar Game delivers. If you liked Death Note or One Outs, this is right up your alley.
Kanzaki Nao is “a foolishly honest girl”. Her relentless honesty and trustfulness leads her to be taken advantage by others, yet somehow, she still has faith in humanity. Suddenly, she gets package with 100 million yen and a note stating that she is now a contestant in the Liar Game Tournament. In this game, all contestants must lie and cheat other contestants out of their money, with losers having to bear the debt. Nao of course, has her money stolen after 1 day by an opponent. Being a broke college student, she desperately thrusts her future into the hands of Akiyama Shinichi, a genius con man. Just what is the Liar Game organisation? With stakes high into the millions, Nao and Akiyama fall deep into the rabbit hole and try to defeat the Liar Game Organisation from within.
This manga is truly a gem. It’s got a lot going for it; intense games and really clever (and unpredictable) twists and solutions, a colourful cast of characters to keep things spicy, and Akiyama who I maybe had a crush on when I was young (lol). Though the art is not pretty, it grows on you and delivers the tone of the manga well. It's also completed so you don't have to wait years for this to be finished.