Ep. 1: Chikane and Himeko celebrate their approaching birthday while Orochi awaken and Souma attacks.

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Chikane and Himeko are nearing their birthday, an event that triggers the awakening of the Orochi. During this time, Souma launches an assault on Himeko, who serves as the solar priestess. He subsequently regains his senses and engages in combat against the second head, identified as Sister Miyako. The episode also features a moment where Chikane and Himeko share a kiss. These events unfold as the characters confront the threats associated with their upcoming birthday and the awakening entities.