かな

Etymology 1

Combination of か (ka, interrogative particle) +‎ な (na, mild exclamatory particle).^[1]

First attested in the late-Edo period as an apparent shift in sense from the Old Japanese and classical usage, wherein the な (na) came to express more a sense of mild doubt rather than admiration^[1] (see that section for more).

Etymology 2

From Old Japanese. First attested in the early 700s.^[1]

From か (ka, particle indicating doubt or uncertainty) +‎ な (na, mild exclamatory particle).

Displaced particle かも (ka mo) around the early-Middle Japanese stage.^[1][2]

Etymology 3

Etymology 4

References