Where does “-aji” come from?

-aji (Swahili) comes from Swahili -i, from Proto-Bantu -ì — Forms agent nouns from verbs.

Ancestry of “-aji”, step by step

Step	Language	Word	Meaning
1	Swahili	-i	—
2	Proto-Bantu	-ì	Forms agent nouns from verbs

-aji — Etymology, Origin & Word History | Etymology Explorer