Where does “我が” come from?

我が (Japanese) comes from Japanese 我, from Old Japanese 我, from Old Japanese れ — nominalizing suffix used to form pronouns, often from demonstratives: one, thing.

我が (Japanese): my; our

Definitions

my; our

Ancestry of “我が”, step by step

我が traces back through two separate lines of ancestry.

via Japanese 我

Step	Language	Word	Meaning
1	Japanese	我	first person singular pronoun: I, me, oneself;...
2	Old Japanese	我	first-person personal pronoun: I, me;...
3	Old Japanese	れ	nominalizing suffix used to form pronouns, often from demonstratives: one, thing

via Japanese が

Step	Language	Word	Meaning
1	Japanese	が	Indicates the subject of a sentence; conjunction;...
2	Finnish	-nka	Forms nouns, mainly bird names (in dialects) and some toponyms

Every word from Old Japanese れ →Every word from Old Japanese 我 →Every word from Japanese 我 →