The Latin Journal was written on December 29, but does not give a year or who wrote it. According to Phi, the diary is actually a research journal that talks about Radical-6 and how it devastated the world, as well as its symptoms. It is also unknown how Zero Sr. obtained this journal, and how it got to Rhizome 9.
In this ending, Sigma, Clover, and Dio investigate the Laboratory and find the journal. After Dio blackmails Sigma, by saying he'll destroy the Axelavir if he doesn't pick Ally. After Dio opens the AB room and everyone else gets back, Phi asks Sigma to look at the journal. After scanning the journal, Phi realizes that she can read page 216.
The page states that Radical-6 reduces the speed of the brain to 1/6 of its original speed. According to the diary, the slowdown of the brain leads the infected person to try to kill themselves. After stating the symptoms of the disease, the journal states that scientists are currently looking into a treatment and a possible cure for Radical-6, but they believe that this could take more than a decade. The journal states that bodies are piling up and that the stench is unbearable. The journal concludes saying that the people who were immune to the virus were locked in underground shelters by the government.
Upon reading this, Sigma and Phi believe that they may be in an underground shelter and that the virus somehow got in, since Quark is infected. However they are skeptical as to why they are playing the Nonary Game: Ambidex Edition as it defeats the purpose of being kept safe in a shelter.
The Latin journal is found in this ending by Alice and K, since they went to the laboratory in this timeline. Alice decides to hold onto it thinking that it is important, however she kills herself after the second round of the AB game, and her body is found by Phi. Soon after, Clover believes that Alice was killed by all of the other players and threatens to kill them all if they don't prove otherwise. Sigma then remembers the Latin Journal from Quark's ending, and Phi takes it from Alice's body. Sigma tells her to read page 216, saying that is proof that Alice wasn't murdered.