Googled it and found out it's a saying or something that's one one of the cards that Kaguya Houraisan owns in one of the game, who's abilities include "The Manipulation of Time and Space". I think I found our Day-Shortener's flavor.
Also, I think HGR has been leaving clues in the flavor, partly because of that and partly because of the message at the beginning of D3. He leaves flavor in the 1st person of someone chasing after someone and seeing a "shrine maiden in red and white" who was dancing, and once they came to their senses after being captivated by the dance, they lost sight of the shrine maiden. N2 is the night that it's most likely Scum tried to kill Chris who with Arti's item was able to get away, and Reimu is described as a shrine maiden in red and white.
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Just that awesome
~InsaneOne