What is eternal darkness in Japanese?

Answer 1

黒代 is the closest thing I could find. Let me mention that just because the kanji used in Japanese names each have a meaning, it doesn't mean that names always convey a special meaning. In this case a meaning close to what you had in mind can be assumed.

黒代 can be read 'kuroshiro' and 'kurodai' and consists of two kanji 黒 literally meaning 'black' but figuratively can mean 'dark' too; and 代 has many meanings but when read 'shiro' as in the first one, it does not mean what we want. Instead when read 'dai' it can mean 'age, times, era, period, etc' so I recommend the second one.

Answer 2

永遠の闇

Eien no yami

Answer 3

暗闇の中で炎

Kurayami no naka de honoo

Answer 4

くらい影 /ku rai ka ge/.

Answer 5

暗い火 (kurai hi)

Answer 6

kurai

Answer 7

kurai

Answer 8

kuraizora

Answer 9

Oinaru yami