[THE UNDEATH MTS (Ayana Mizuki)] Shu to majiwaritakuba kurenai to kase -If you want to commune with vermilion, turn into crimson. (Touhou Project) [English] [Pedy] [Digital]
The way that guy thinks of Remilia reminds me of Eternal Melody's song about her, Lunatic Red. If you're curious, looks up Releska's translation for it. Since the lyrics are pretty long, I'll just add a short bit to this comment. (It's a fantastic song btw!)
"I embrace you, illuminated by the moon. Naked sins are so sweet—they gnaw away at me. My overflowed love will kill you. My tainted love will violate you and then melt away…
Ah, your final moments, seen through your eyes, are so precious. On a pristine cross, you spit out meaningless words."