Shingeki No Kyojin Ova - Episode 1 -

This was the first time in the series a "mindless" Titan was shown to have the capacity for speech and complex emotion (reverence).

During the 49th Exterior Scouting Mission, Hange Zoë is obsessed with capturing a Titan for research, despite Commander Erwin Smith’s refusal due to the high risk. While pursuing a Titan into a forest, the scouts find the decapitated body of a soldier, Ilse Langnar , hidden inside a tree, with her notebook nearby. Shingeki no Kyojin OVA - Episode 1

The episode follows two parallel timelines: the present search by the Scout Regiment and the past account written in a diary. This was the first time in the series

The discovery of the notebook and the evidence that Titans might be sentient changed the Scouts' approach, finally convincing Erwin to allow Titan capture missions. Watch Information The episode follows two parallel timelines: the present