They are offsprings of a god who turned into a demon(it happens a lot on east asian mythology, by which I mean chinese korean and japanese). The reason this happened is because their father didn't go to where he was supposed to go(Izanami shrine I think's the name) during october and instead stayed behind to protect his son.
Ayato died to simply protect Yuzuru from their father.
Yuzuru was scared that he'll become just like his father so the solution he thought was to go back to their home, kill his father and take responsibility, in other terms, he became a god, a replacement of his father.
This is all just a theory of course, but them killing themselves doesn't really fit in well. The sacred tree was there remember? And Ayato said it's their home. Another thing is, I think Yuzuru would have become a monster if he kept on staying as 'neither human, nor god' since 'gods can never be with humans' rule. (I know there are the demigods but seriously, it's the closest I could think of why. And it makes sense why his father turned to a demon)
So I think here's what really happened.
They didn't die. xD
They are offsprings of a god who turned into a demon(it happens a lot on east asian mythology, by which I mean chinese korean and japanese). The reason this happened is because their father didn't go to where he was supposed to go(Izanami shrine I think's the name) during october and instead stayed behind to protect his son.
Ayato died to simply protect Yuzuru from their father.
Yuzuru was scared that he'll become just like his father so the solution he thought was to go back to their home, kill his father and take responsibility, in other terms, he became a god, a replacement of his father.
This is all just a theory of course, but them killing themselves doesn't really fit in well. The sacred tree was there remember? And Ayato said it's their home. Another thing is, I think Yuzuru would have become a monster if he kept on staying as 'neither human, nor god' since 'gods can never be with humans' rule. (I know there are the demigods but seriously, it's the closest I could think of why. And it makes sense why his father turned to a demon)