The Japanese ogre — and, as a prefix, it just means 'insanely'.

What a Japanese person actually thinks
Strong and genuinely native, unlike the imported 悪魔. The slang usage keeps it feeling current rather than antique, and 鬼 also appears in the standard phrase 鬼のような ('like a demon') for someone relentless.

Meaning

Literally: demon; ghost
Actually: An oni: horned, club-wielding, from folklore. Also a productive slang prefix meaning 'extremely' — 鬼強い (insanely strong), 鬼かわいい.

Scores

Naturalness●●●●●

Extremely common, both literally and as slang.

Coolness●●●●●

Ten strokes with an unmistakable silhouette. One of the few 'dark' characters that doesn't read as adolescent.

Watch out

lowAlso used for a strict or merciless person — 鬼上司 is a boss from hell. Not negative exactly, but severe.

On skin

鬼

Orientation: either

Bold brush.