I like the world these characters are in, and the whole 'water people and land people should not mix' theme (even though there's already evidence that the reason for it might be complete BS), but the main characters themselves don't really do me much. Hikari's possessiveness over Manaka is terribly annoying (why can't he just tell her he's in love with her?), and Manaka herself is a bit too childish for my likings. Chisaki seems to be the only mature girl of the bunch, and she keeps getting the short end of the stick, given that Hikari won't give up on Manaka anytime soon.
I'm still following this, because I'm curious if this will change anytime soon, but it's not really looking good right now.