Diary of the 5th Commander

The year is 853 in October. Section Commander Hanji Zoë, has two Titan hybrids that she's raised with Levi. Until one of the Hybrids discovers an old crate with documents and a map leading to an 107 year old diary that was written by Hanne Wolff, the 5th Commander of the Scouting Regiment, and an old abandoned asylum's location is inside that crate. The 5th Commander's diary uncovers a shocking experience of a unknown breed of Titan at the time, that he began to call Thanatos. But during Levi and Rupert's search for that said diary, they come in contact with a somewhat old Titan with Jaeger Titan features.