NON-BL LIST WITH LESS THAN 9 RATINGS

MC was transported to novel of his choice after dying, but instead of protagonist he became a side character.

It currently has a 9.0 rating but I know later on it will drop again.

Summary
"I never want to lose someone important to me again." One day, I, a nerdy and bullied boy, was provoked by my classmates to go to an SS-ranked dungeon. Facing an SS-class black dragon that I couldn't do anything about, my chances of survival were zero... At that moment, someone appeared before my eyes... This is the story of the bond between the strongest slime and the weakest me, as we grow together.

Summary
Forensic Scientist Kim Junghoon lies dead in the National Forensic Services autopsy room. He died full of regret after witnessing his work partner of 20 years, Kim Sangjin, distorted his very own autopsy report when he was still conscious and accused him of committing suicide. Right after he passed away, Kim Junghoon opened his eyes once more and found himself back in 2002 when he was still a rookie in the National Forensic Service.