Chainsaw Man and Jujutsu Kaisen both start with the main protagonist merging/combining with a demon or devil; CM's being Pochita and Denji, JJK's being Yuuji and Sukuna. Jujutsu Kaisen and Chainsaw Man see the protagonists as someone/thing that needs to be eliminated but will let them live on certain conditions, such as fighting against devils on a team or finishing what they started with the merge concerning a demon.

Jujutsu Kaisen

HIGH

You'll want a pretty high violence tolerance to enjoy this.

Jujutsu Kaisen

EXTREME !!!