残骸 means “wreckage” or “remnants left behind after something is destroyed.” It is a vivid, dramatic word that is less common in everyday lyrics than simply saying “pieces” or “ruins.”
In the song, 愛の残骸 means “the remnants of love,” describing the scattered emotional remains left behind in an empty room. The word gives the failed relationship a powerful, almost disaster-like image.
This is a love song with its fangs out. The woman singing knows exactly what she has got herself into. He is her type, a bit cruel, and very good at getting her to pay for everything: "あなた貢がせ上手" (you're so good at making me spend on you). The verb 貢ぐ means to shower someone with gifts or money, and 貢がせ上手 is a sharp little compound for a man who is skilled at making a woman do it. His demands even arrive in quotation marks: "「あれ買って もっと愛して」" ("buy me that, love me more").
The title is the whole idea. Only after she has fallen does she get it: "あなたはヴァンパイア" (you are a vampire). From there the song gets violent fast. She wants to cut off the tongue that tangles with hers and snap the fingers that caress her, which is a lot, and that is the point. By the end she is begging him to drain her completely, "全て吸い取って 骨の髄まで" (suck everything out of me, right down to the marrow), and offering herself on terrible terms: "一人にしないで 奴隷でイイから" (don't leave me alone, I'll even be your slave).
What stays with me is how clear-eyed she is. She calls herself "バカな女" (a foolish woman), says she won't believe in love if it hurts this much, and then admits "あなたの嘘をまだ どこかで信じてる" (somewhere I still believe your lies). Watch for the English loanwords Janne Da Arc scatter through the verses, like インスピレーション (inspiration) and ナビゲーション (navigation): they give the lyrics a cheeky, half-joking edge against all that desperation.