"Attack on Titan" chapter 86 is expected to solve several of the series' mysteries, which may include the history of their world.

"Attack on Titan" chapter 86 will continue to delve on the three notebooks from the basement, Yibada reported. It is speculated that one of them contains the history of the world, the other talks about the origin of the titans and the last is about the Coordinate.

According to the report, the history of the "Attack on Titan" world is the most controversial issue in the series. Information about that is strictly prohibited and the first residents who built the wall had their memories manipulated.

Aside from the three notebooks, it is said that the key that Eren is holding is not of the basement door, contrary to a previous belief. Instead, it will open a secret drawer in the table where his father's notebooks are located. According to HOFMag, this is highly likely because in chapter 85, the key does not actually fit the door and it was only opened when Levi knocked it down.

Aside from providing answers, "Attack on Titan" chapter 85 opened a door to a new mystery. At the back of the notebook, the writer claimed that he was from outside the walls and said that "humans are not extinct at all."

This is huge news, as any information from beyond the walls are virtually unknown to those who were born inside. It will reportedly prompt new questions about the location of other human settlements and if they are also at the mercy of the titans.

When the end of chapter 85 featured a portrait of a father, mother and their son, questions popped up regarding the child's identity. It is speculated that this might actually be Zeke.

"Attack on Titan" chapter 86 is set to be released in the Oct. 8 issue of Shueisha Shonen Jump Weekly.