bullseye
The answer is: The ('s) is shows for belonging , so the word (useless) being said that the "Duke('s) daughter" is the "useless" one here. *My main language is not english so I hope you can understand what I'm trying to say*(￣∇￣")
Sorry! I forgot to mention the main things that made most of people confuse, about the using of ('s): When the author write, "Duke('s)", the word before *___('s) gonna be said to the person after the ('s), as if the "Duke" word doesn't exist, it being write just to inform who is the "Daughter" belongs to, and the obvious answer gonna be the"Duke", this is where the only place the word "Duke" being use. *That's all I know-?* ╮(￣▽￣)╭
The title is confusing me like why is the duke the useless one?? Shouldn't it be "I just want to be the duke's useless daughter"?? And this feels like a chinese manhwa, you know those fast paced ridiculous stories with questionable English translation.