Yami
the answer is "Yami"
to say angel of darkness, say: "Yami no Tenshi"
Wolf of darkness is ankoku no ookami in Japanese.
暗黒の王子 /an ko ku no o jou/ is Japanese for 'Prince of Darkness'.
You may say 'kurasa,' written: 暗さ
Yami no hi would be flame of darkness
Kami is already Japanese and means God/Paper/Hair depending on the kanji. When adding a word in front of kami, it changes to gami. For example, shinigami, the death god.Shadow god would be kagegami, black god would be kurogami, and darkness god would be yamigami.
In Japanese it means Darkness
Kurai is dark in Japanese.
闇
Wolf of darkness is ankoku no ookami in Japanese.
暗黒の王子 /an ko ku no o jou/ is Japanese for 'Prince of Darkness'.
'Protector of darkness' may be translated as闇の保護者 (yami no hogosha) in Japanese.
yami no hi
Yami no kiba
暗さ (kurasa)
暗闇 kurayami.
闇 YamiOr, alternatively, kurasa.
You may say 'kurasa,' written: 暗さ