For anyone that remembers thriller bark or the time skip, there was a character referred to as "princess Perona", aka the "ghost princess".. doesn't it seem a little odd that imu's devil fruit has been compared to moria's? And their names rhyme? ( Not sure if that's the case I'm Japanese but still..) Oda is not one to leave things up to chance, in fact I'd say every mystery in the story that could possibly be a coincidence is almost surely intentional.. nevermind the fact that we really have no idea where she came from (and she is oddly comfortable around mihawk, someone who has been stated to have similar eyes to imu.)
Remember the Giant shadows near thriller bark that has long yet been unexplained? I think this is actually the best explanation.. its imu and the five elder stars.