This series for me wasn't so much of a sequel, but more of a natural progression of the original. Due to the relaxed nature of the first, it simply continues where ARIA the Animation left off and lets us even further into its world. As far as characters go, there is a one new introduction to be made and futher development into a few others, particularly those of the Prima Undines and Grandma. Other than that though, most of the series feels like an extenion of the first one, which really makes for a wonderful series when you think on it!