The PV uses color imagery in the order yellow, green, red, and blue, referencing the order of the novels in The Daughter of Evil series.
The niconico upload is described as "At the top of Marlon's Castle Hedgehog is a looming tower. Also known as the 'Heartbeat Clocktower'. The ticking of the second hand resounds out. A woman waits in a room on the top floor. The curtain rises on the young king's final battle, and then, the curtain closes on the story."
mothy's official playlist lists the song as occuring in EC 505 and describes it as "The Hedgehog Upheaval."