Asmoday is the Ruler of Space[4] among the Four Shades of the Heavenly Principles. She is the mysterious god responsible for separating the Traveler from their sibling at the start of Genshin Impact.

She appears in the opening cutscene, in which the Traveler tells Paimon how they ended up stranded in Teyvat. She introduces herself as the "sustainer of heavenly principles" - what this means is not yet known.