Where does “宮号” come from?

宮号 (Japanese) comes from Japanese 宮, from Middle Chinese 宮.

宮号 (Japanese): the title of a 宮家, always suffixed with 宮, also used as a title for its patriarch and matriarch; not to be confused with 称号, which is constructed and used similarly

Definitions

the title of a 宮家, always suffixed with 宮, also used as a title for its patriarch and matriarch; not to be confused with 称号, which is constructed and used similarly

Ancestry of “宮号”, step by step

宮号 traces back through two separate lines of ancestry.

via Japanese 宮

Step	Language	Word	Meaning
1	Japanese	宮	the place where a god resides: a shrine; a temple...
2	Middle Chinese	宮	—

via Japanese 号

Step	Language	Word	Meaning
1	Japanese	号	number
2	Middle Chinese	號	—

Every word from Middle Chinese 宮 →Every word from Japanese 宮 →