This chapter opens with a flashback to the beginning of the previous chapter, in which the narrator explains that he has just returned from the battlefield of the "dark labyrinth," a game in which ten pairs of players compete against one another in order to win the battlefield. This round of the game is called "Concentration." The key to victory in this round is "concentration between a couple." In other words, if one player kills another player, that player's death is a failure in the game. In this case, the key is that the two players must be in the same place at the same time. The map of the labyrinth appears every ten minutes and every five seconds, and the location of the central escape in the labyrinth is revealed once every 5 seconds. The narrator is amazed that he can remember 20 players and that the labyrinth begins here. He is able to break open the labyrinth by using his "iron fist," which is a special ability that allows him to move through the labyrinth in a single motion. This ability is limited to a distance of 5 meters, but the narrator is certain that he will be able to use it to open the