Attack on Titan OVA (2013) - Episode 8 - Lost in the cruel world [English Subbed]

Summary :- Before the operation to take back Wall Maria, a Titan guillotine is seen killing Titans as Mikasa Ackermann begins to worry about Eren Jaeger. She recalls the time when she, Eren, and Armin Arlelt reminisced about the old days. Mikasa then begins to worry what Eren will do after the retaking of Wall Maria. She recalls another memory during the Struggle for Trost, when Armin informed her of Eren's death.

In shock, Mikasa experiences a different reality where her parents are alive. Inside her forest house, Dr. Jaeger brings Eren with him during a medical visit to the Ackermanns, and the two kids quickly become friends. Eren mentions to Mikasa that he will be leaving the Walls soon in a hot air balloon in order to explore the outside world, and upon reaching the place where he told her to meet him, Mikasa finds Armin alone, and he tells her of how Eren died to save him.