Complex sentence: At the end of the anime, Mytho's real name is revealed to be Siegfried, the name of the Prince in the ballet "Swan Lake", from which the series borrows many plot elements.
Split into simpler sentences: At the end of the anime, Mytho's real name is revealed to be Siegfried. Incidentally, this is the name of the Prince in the ballet "Swan Lake", from which the series borrows many plot elements.