Sounds similar to how the monarch of Malaysia is chosen. https://en.m.wikipedia.org/wiki/Succession_to_the_Malaysian_thrones
The next national ruler is chosen from the nine hereditary state sultans. It's technically an elective monarchy, but there is a conventional rotation order among the states.
Not to stifle further discussion, but this Wikipedia page has a wealth of examples
https://en.m.wikipedia.org/wiki/List_of_placeholder_names_by_language