I would ask you to explain this dying regret and what it means but I'm not interested in pointless discussion, you see, there's a big difference between "I need to do x" and "I wish I had done more of x", you feel me? It's quite amazing that you think she achieved "full camouflage" just because she said it, can't be that a character can believe something that's not true... anything said by a character is obviously fact, the literary technique of taking everything literally. I also love your "realism" take on this wound you carefully inspected... actually made me smile.
There is no magic in this story, the black haired girl(the one from Hans Christian Andersen's tale, if you will) dies because she's just a poor street person selling something nobody wants to buy and then the main character hallucinates her. Jiro Matsumoto characters are almost always insane.