A Game Master (ゲームマスター Gēmumasutā) is an Officer-rank Reaper selected by the Composer to assign the missions for the Reapers' Game of that week. While the rank of Game Master doesn't affect one's power, it does grant more liberties than a non-Game Master has. For example, Game Masters have control over all the Reapers below the rank of Conductor. There have been three known Game Masters: Yodai Higashizawa (by proxy, later officially), Sho Minamimoto, and Mitsuki Konishi.
The Game Master's main purpose is to assign the missions for that week, which usually last for a few hours, and enough for one each day. These missions can also last for more than one day. While a Game Master can choose to shirk his or her duties and not assign any missions without receiving any penalties, this is both frowned upon by the Conductor and can be deadly for the Game Master. Only one Game Master has ever chosen to do this, and that is Sho Minamimoto, who was creating Taboo Noise refinery sigils, and even then he had a back up plan in order to be "reborn" with those sigils.
The more Players left alive to combat the Game Master, the lower the chances of him or her surviving. This is because the final mission on Day 7 is usually to defeat the current Game Master (though Players don't have to kill him/her, just defeat the GM, however, it's possible for them to do it)
- Can assign one mission per day during the Reapers' Game.
- Can erase Players on Day 7.
- Controls all Reapers below the rank of Conductor.
- Free to erase other Reapers without punishment (Mitsuki Konishi killed 777).
- Can assign a temporary Game Master to take their place if they ever need to vacate the Underground.
- Has a Noise Form.
Achieving the Rank
The only way to become a Game Master is to be chosen by the Composer. The Game Master isn't really a "rank", but rather a temporary title and privilege, since one is only Game Master for a period of seven days.