Ep. 1: Rin and Rina search for water in a red fog-covered world while Ritsu waits far away.

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The narrative begins in a desolate environment shrouded in red fog, where a decaying building serves as the setting for the opening scene. Rin, characterized by her updo hairstyle, and Rina, who wears pigtails, are depicted searching for water within this structure. Their objective is to locate a vital resource amidst the ruins. As they prepare to communicate their findings to Ritsu, who is positioned at a distant location, their mission is abruptly interrupted by an unexpected crisis. This sequence establishes the harsh conditions of their world and introduces the primary characters and their immediate struggle for survival before the incident occurs.