A great-looking character with strong 'my dark side' energy.

What a Japanese person actually thinks
Chūnibyō adjacent — the register of a teenager's manga alter ego. That said, the character itself is magnificent: a sound sealed inside a gate.

Meaning

Literally: gate + sound
Actually: Darkness. Also the black market and the criminal underworld (闇金 loan sharks, 闇バイト illegal gig work).

Scores

Naturalness●●●●●

Real word, currently very much in the news because of 闇バイト crime recruitment.

Coolness●●●●●

Visually one of the best kanji there is. The meaning is what drags it down.

Watch out

mediumIncreasingly associated with organised crime and scam recruitment in current Japanese usage. That association is getting stronger, not weaker.

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幽玄 yūgen
profound, mysterious beauty beyond words

If the appeal was depth and mystery rather than edge, this is the real aesthetic term — and it's beautiful.
影 kage
shadow

The melancholy version, with no criminal overtone.

On skin

闇

Orientation: either

Bold, large. The gate radical must not close up.