Liar Game, Volume 1 by Shinobu Kaitani

In this gripping psychological thriller, an unsuspecting and honest young woman named Nao Kanzaki finds herself entangled in a high-stakes game of deception and manipulation. After receiving a mysterious package containing a large sum of money and an invitation to participate in the "Liar Game," she is thrust into a world where trust is a rare commodity and betrayal lurks at every corner. Desperate to escape the game's clutches, Nao seeks the help of a cunning ex-con artist, Shinichi Akiyama, to navigate the treacherous challenges ahead. Together, they must outwit their opponents and uncover the truth behind the sinister organization orchestrating the game.