Two Choices

 Two choices (二回の選択肢, Ni no sentakushi) is the fifth chapter of Volume seven and 57th chapter overall.

Plot
Light instructs Misa to continue writing the names of criminals in the Death Note so that they can avert suspicion once again.

L continues to grill Rem with questions about the nature of the notebook. When he sees Light’s tenacity in staying with the investigation, he wonders if he’s the one now being watched.

The next day, Aizawa comes by with the news that Kira has continued killing criminals once again. Rem realizes that it must be Misa doing this.

L notes that it’s suspicious that there’s another notebook out there, and this happens the moment that Misa is set free. Rem begins to worry about Misa, and Light smiles. L talks about finding out the identity of Kira and forcing them to write his own name down in the notebook in order to test it out. Rem realizes that eventually L will find Misa, and most likely, she will receive the maximum punishment.

Then, it dawns on Rem. This is part of Light’s plan. Light wants Rem to save Misa’s life by writing down L’s name on the Death Note. Because she will write down L’s name to save Misa’s life, Rem will most certainly die. However, she can’t kill Light in retaliation because he is the only one that can possibly avert suspicion away from Misa. She will be caught quicker if Light dies. Rem now has a choice: either both Rem and L die or Misa dies.

Meanwhile, L is still terribly confused about the whole ordeal, especially about the 13 day rule. He finally decides to test out the 13 day rule by having a criminal on death row write down their own name in the Death Note. If the criminal is still alive after 13 days, then the rule will be proven to be a fake. If this happens, Misa will certainly be captured.

Rem panics and leaves the room.

While Watari is talking to L over the computer screen, he suddenly collapses.

Conception
Ohba said the chapter's title "Two Choices" is about Rem's decision of whether she should save Misa and die, or let Misa be captured and put to death.