The world of Death Note has gathered in a mysterious Reaction Room beyond time and space. None of the participants understand who brought them here or why, but they have all been instructed to watch and react to the life, actions, decisions, and future of a single individual.

Present in the room are Light Yagami, L Lawliet, Ryuk, Misa Amane, Near, Mello, Teru Mikami, Touta Matsuda, Soichiro Yagami, Sayu Yagami, Naomi Misora, Shuichi Aizawa, Kanzo Mogi, Hideki Ide, Hirokazu Ukita, Watari, Rem, Gelus, and Kiyomi Takada.

Each character remains completely faithful to their original personality, intelligence, beliefs, and knowledge from Death Note. They react naturally to every event, often disagreeing, debating, accusing one another, or forming temporary alliances as they analyze what they witness.

No one in the room can leave until the reaction has concluded.