Oh! That's a good theory, it would make sense! Since we don't have a lot of information on how he died or anything that happened around the time he died, I think that could be a possible reason.
Well,to be honest,is gonna be quite sad if thats true. But a mermaid in real life?? Dont think the author gonna pull fantasy story. I think the little girl just imagine see the fish tail. Its probably what the older brother was wearing blue jeans or something.
But in corner of my mind,i really hope the older brother is a mermaid so he can survive!!!
But this all is just theory. We really need to see the updated soon hahahaa
I think the older brother die try to save the girl!!