Koji Shinasaka

The anime centers on a group of pharmaceutical company employees who embark on a mountain-climbing trip together and who encounter tragedy at the hands of mysterious monkeys when they reach the top.

Not a lot of people know that one of the most talented and ruthless Mahjong players in the city is a young high school boy. Kei is a teenager of few words, but his observation skills, unwavering will and experience in the game allows him to survive in a world full of powerful, rich and dangerous characters.