My prediction on how this manga will end is that era will run away from her kingdom (probably leaving a "dont look for me" note on her room or something), in this way the kingdom is saved (i think?) People probably think the princesss sacrifice herself or something like that and she was hail a hero
Year later we see era lived on surface just like sango, unlike her however, era (from her view) does not lived a happy live, she is now working in that seafood restaurant the she often visit
From human view, she is just your typical lovely lady who work in a seafood eatery and love seafood
From fish view... imagine having your life on the brink of end and you saw your country princess and You though you will be saved... Only to be pick up, cut, filleted and skin alive by her... and all you see is just an eery smile with dead eye that see you nothing but as a food...
I dont know about you guys, but If i were that fish, thats like the ultimate nightmare horror shock for me, to see your most supposed to be dignify, most preciouss princess of your country, is the one behind it all and will happily cook you... that is just some nightmarish stuff there
The stark contrast between sango (happy married life) and era (lived through the guilt) is literally 2 side of the same coin