In episode 10 of Dusk Maiden of Amnesia, Teiichi relived the memories of Yuuko's death through her eyes. Sixty years ago an epidemic was ravaging the town where Seikyou Academy is located. Yuuko was taking care of a little girl, Asa (who was probably already infected). Yuuko's sister, Yukariko, opposed this, but good hearted Yuuko wanted to help as much as she could. Things turned horrible when some crazed adults decided to sacrifice Asa in the hope of ending the epidemic. Yuuko went to Asa's rescue and ended up being the sacrifice instead.
This was an emotional episode. There were not many new revelations because most of the information in the episode has been revealed during the series. The most significant revelation is that Yuuko bitterly accepted her fate to be a sacrifice, but she was forced by the crazy adults. This was a very good episode, but I will only give it a 9 out of 10 because most of the information from this episode was previously revealed.