This anime--being from Japan, created by Japanese people with a Japanese audience in mind--is more likely than not referring to the coeurls of FF than from any other fiction.

This does not mean Square invented coeurls. This does not mean D&D invented coeurls. In fact, it doesn't matter who invented coeurls first. What matters is what is most recognizable to the audience or, you could argue, what the author intended to be recognizable.

In literature/film/theater, this is called allusion.

In anime and video games, it's apparently flamebait.