The girl who turned demon that lost it and could only replay memories that she had. Meanwhile for Sadanaga, even if it was temporarily, he wanted to give the girl happiness. Of course, when he came back to the real world, he aged up and couldn't return to the Miura family. After all he couldn't explain why he suddenly aged. Perhaps he requested to his parents to forget about him. Maybe Naotsugu's mother sad he only had a mother because she wanted him to move on.
One thing is clear and that is Naotsugu knew his brother well, and he would stick behind his beliefs. Considering he couldn't be part of the Miura family. At least he could be with his new daughter. The twist that Ofuu has for her father makes so much sense because Sadanaga saved her when he had no reason to. Though Ofuu being a 200-year demon really makes things add up as her wisdom with is really well done. It also comes from her experiences as well.
This arc was a pretty big one for Jinya. In many ways, seeing the despair Ofuu went through and Sadanaga saved her. I wonder if this will give him aim to save Suzune as she is clearly in despair at this point. Of course, he can't forgive her for killing for Shirayuki, but not all of his memories with Suzune aren't all bad. Still, they are siblings and the bond a family can bring to a person can't be lightly stated. It can really save a person. The biggest thing that Ofuu points out that I love is that Jinya can look past his purpose. Perhaps to the point that he isn't consumed by revenge as time has moved on.
