The Demise of the Pocket Knight

You are a student at S University. Today, your group gathers at a board game store in this city to play a jubensha game. You've chosen a game involving a medieval knight duel. However, as the game progresses, everyone starts recalling some unpleasant memories. Intuition tells you that things aren't as simple as they seem, but it's too late -- the game has already begun. Each person's hidden secrets will inevitably be exposed, and you are destined not to leave unscathed. It seems this is more than just a game...