From Shogakukan Asia:

In the underbelly of society, “Dark Games” are used to settle disputes between opposing organizations of the underworld. Tohru Kageura, a strange boy who possesses a special ability to “see” the Death Deity, is forced to participate in a Dark Game of Buddyfight to pay off his late father’s debt. However, the consequences of losing a Dark Game are a lot more deadly than a normal card fight – one that could cost the player his life!