Older Nanao

An older man also named Nanao.
He is revealed to actually be the younger Nanao's father, the original Nanao, who 25 years ago was fed mermaid flesh by his mother, which started the rumor about the woman who poisoned her son.
He was split apart from his mother after the incident, but years later once he had a child, his mother showed up and kidnapped the child, who she named Nanao. Now the older Nanao has returned to convince his mother to give his child back.