I'm pretty sure it's the daughter that dies. Even some native Japanese were confused about this, going by the comments in Nicovideo.
Although the sinking of Nagara was concealed by the Navy, rumors spread widely in town as there are many eye-witnesses.After the war, my daughter gave birth to a child but died of an illnessHeading out to sea over Nagara's final resting place,A lone woman begins performing the last rites for Nagara"You can catch sea breams around the warship Sone". There were rumours that the artificial reef the fishermen called Sone was the sunken Nagara.
It seems that Sone = reef in some Nansei islands dialect used in Kyushu. So "Warship Sone" = "Artificial reef created from a warship", in this case referring to Nagara"A few days later, the rumours spread to us. My daughter and I clasped our hands at a Buddhist altar, crying as we prayed.
