The OP Nagi no Asukara’s second cour (which Hannah is four episodes from completing) does a fine job eloquently and efficiently sets the quiet, bittersweet mood and portrays the gorgeous, somewhat otherworldly setting of the show it precedes. This is the second version of the second cour OP, which is used once Manaka is retrieved from the ocean.
There’s a lot going on here, with the sidelong glances, longing, heavy symbolism of things lost and gained, time moving forward while other things stand still, and evoking the occasional urge to lock all of these people in small room and not let them out until they’ve all notified one another who loves whom and come up with a way to proceed!
RABUJOI - An Anime Blog 