RE: Zero -Starting Life in Another World-, Chapter 4: The Sanctuary and the Witch of Greed, Vol. 11 (Manga)

The Origins of the Sanctuary, and Emilia's Sealed-Off History--In the world of the past, Echidna and her companions face a sudden assault by Hector, the Devil of Melancholy. With this crisis upon them, Ryuzu makes the decision to sacrifice herself. And in the present, Emilia glimpses in her Trial an unfolding tragedy from her youth as the arrival of the beings Regulus and Pandora signals a precipitous turn for the worse...!