It just says 'death'. Blunt in a way that reads adolescent, not dark.

What a Japanese person actually thinks
Reads as edgy-teenager rather than menacing. Japanese people generally find 死 alone a bit crude — it's the word on a death certificate, not a philosophical statement. Also, 死 is homophone-adjacent to 四 (four), which is why Japanese buildings skip the 4th floor.

Meaning

Literally: death
Actually: Death. The plain noun, with none of the poetry English gets from words like 'mortality'.

Scores

Naturalness●●●●●

It's a real word, just an abrupt one to display.

Coolness●●●●●

Visually strong, semantically flat. It has shock value and nothing behind it.

Watch out

mediumGenuinely unlucky in Japanese culture because of the 死/四 homophone. Displaying it is closer to taboo than to edgy.

Get this instead

諸行無常 shogyō mujō
all things are impermanent

If the idea is 'everything dies', this is the real, weighty way to say it.
生死 shōji
life and death

The Buddhist pairing. Holding both is far more interesting than just the one.

On skin

死

Orientation: either

Mincho, if you keep it. Brush makes it look like a horror-film poster.