When you think about it, the RPG that Yama play with his friends after he was released from his hospital is foreshadowing Rui's death. You know how Rui got captured by the monster in the game? Despite how everyone in the party tried to save her, even with Yama trying to draw monsters' attention to himself so that others can save Rui; they failed. When you think about it that way, how the game ends for them foreshadow what will happen to Rui in the end.
