Royalty and Nobility
Being a royal, means you are in the top. Ruling and commanding, this position mostly goes to the King and his family.
And being a noble, means you have a high position. But not high enough to rule. This position usually goes to ambassadors, generals and council member.
But no.. In this kingdom nobles are honored slaves. It doesn't matter if you were born a high noble, at moment you are born by a noble you will immediately be a slave to the royals.
As a matter of fact in this kingdom, being a slave is the richest job that anyone could have. Anyone would die to be a born noble.
Especially a very submissive blonde
that comes from the Nobles of the Namikaze Clan.