Countdown

 Countdown (カウントダウン, Kauntodaun) is the sixth chapter of volume two and thirteenth chapter overall.

Plot
Light decides to eliminate Raye Penber’s fiancée immediately before she tells anyone her suspicions. He starts by agreeing whole-heartedly with Maki’s suspicions and asking her the date and time of the bus jacking. Light whips out a piece of paper from his pocket, which turns out to be the Death Note. He pretends write down the information, but he is really writing down Shoko Maki’s name and cause of death as “suicide, starting at 1:15 p.m”. Light notices Ryuk once again chuckling to himself. Light talks to her until 1:15 p.m., but nothing happens. It finally hits Light. The name is an alias!

Ray Penber’s fiancée decides to go back to headquarters, and Light is determined to stop her and find out her real name. In a moment of frustration, he says that she is a woman and he will use force if he has to. Ryuk once again offers to trade the Shinigami Eyes for half of his life span, but Light refuses.

When L is finished investigating the task force, Watari, L’s shadowed assistant in coat, finally reveals himself to be an old man in a top hat. Watari brings each of the investigators fake IDs to use from now on.

Light figures that he has five minutes to figure Maki’s real name before she reaches the NPA building.

Conception
The title "Countdown" was chosen since Light was counting down the seconds until Naomi would reach the NPA headquarters, and he was counting down the seconds until Naomi's death was triggered.