Lucifer

I would bet good money that Kim Ji Woo watched "One Million Stars" before writing "The Devil". There are numerous parallels between the plots, characters and themes as both shows explore issues of moral culpability and the lasting impact of violence. There are significant differences as well, and it's fascinating to watch how the shows diverge despite starting with similar premises.

In both dramas a mastermind gives his opponent clues in order to uncover the truth they want to reveal. The feelings of both dramas are very similar, with every episode revealing a small part of a bigger picture. Also both dramas star Uhm Tae Woong (although in very different roles).

1) They are revenge drama
2) Both involved an unsolved murder
3) The main character mission for revenge started when he was a teenager.
4) The main character sends clues to certain people.
5) The author uses western style art as a medium in Shark case it is Greek Mythology and in The Devil case it is Dante's Inferno.
6) Both men stare at the same potrait to get inspiration

Inagaki Sakura is a dedicate girlfriend, supporting her infamous actor boyfriend, Yokota Kohei, on a low pay rate. But as he became famous, her dumped her for the influencer, Inoue Madoka. Sakura plans revenge, and the millionaire, Ichinose Keita, offers help, but in return, signs a contract with the devil. Sakura doesn't hesitate to accept and starts her revenge.

Both are mystery, crime dramas with extremely well written plots.