The reversed vocals in Kunitsu-Gami are from Kunitsu-Kami.

A video showing the reversed vocals are from Kunitsu-Kami.

Cursed Soh, who can only be fought on NG+, has long nails. I wonder...?

Here are the lyrics. In the video I cut out the repeated lyrics so here's the full thing:

昼は良い良い夜は怖い
宵々来るは世の罪か
眠らぬ童は手を引かれ
陰に蠢く蟲となる

季節の中に消えようと
今は畏れないで

十二の面は舞い踊り
笛と哭声鳴り響く
畏れを成せば夜に掴まれ
穢れの花は世を乱す
指折り数える御霊を持ち
畏れを祓い罪の血を絶てば
常しえの暁が訪れ
天つ雲居の平らかな
世を照らす日明り

季節の中に消えようと
今は畏れないで

十二の面は舞い踊り
笛と哭声鳴り響く
畏れを成せば夜に掴まれ
穢れの花は世を乱す
指折り数える御霊を持ち
畏れを祓い罪の血を絶てば
常しえの暁が訪れ
天つ雲居の平らかな
世を照らす日明り

 陰に隠れず出ておいで
畏れないで畏れないで
ほら爪の伸びた手の平を
しっかり握って行きましょう

--

The daytime is fine, but the night is frightening.

Is it the sins of the world that bring night after night?

The sleepless child is led away by the hand,

and becomes a worm lurking in the shadows.

Even if we disappear into the seasons,

do not be afraid now.

Twelve masks dance and fret, and the sounds of flutes and weeping resound

If you fear, you will be seized by the night

The flowers of defilement disrupt the world

Hold onto the spirits you count on your fingers, and if you dispel fear and sever the blood of sin, the eternal dawn will arrive, and the light of the sun illuminating the world, the calm of the heavenly clouds

Even if we disappear into the seasons,

do not be afraid now.

Twelve masks dance and fret, and the sounds of flutes and weeping resound

If you fear, you will be seized by the night

The flowers of defilement disrupt the world

Hold onto the spirits you count on your fingers, and if you dispel fear and sever the blood of sin, the eternal dawn will arrive, and the light of the sun illuminating the world, the calm of the heavenly clouds

Come out, don't hide in the shadows

Don't be afraid, don't be afraid

Now, let's firmly grasp the palm of your hand with its long nails

and go.

This english translation is different to the video but it's saying the same thing really. Subjects can be vague so the translation can be a little strange sometimes.