As a word, Kamui (カムイ), which is normally written as Kamuy (カムィ), refers to a spiritual/divine being in Ainu mythology. Personified deities like Repun Kamuy (god of the sea, depicted as a killer whale or an orca) and Chikap Kamuy (god of the owls and the land, depicted as a great owl) often have Kamuy applied as part of their names.
Bearers of this name include manga artist and character designer Kamui Fujiwara (藤原 カムイ) (1959-) and racing driver Kamui Kobayashi (小林 可夢偉) (1986-).
This name is rarely given to boys, if given at all.
Other Kanji combinations are also possible.
Famous bearers of this name are Japanese football player of Korean descent Kazunari Okayama (Kang Il-Sung) and Japanese Nippon Professional Baseball player Kazunari Sanematsu.