I honestly have no idea what manga this is or when did i read it
I was in the same boat. I started reading this latest chapter and had absolutely no idea what was going on and nothing was coming back to me...
But the basic premise that I'm remembering after re-reading the first few chapters:
The MC ("Hikaru") takes over the body of some dead guy in exchange for killing someone. MC becomes a powerful assassin with his use of his points on his "soul board" / skill tree system, which almost immediately gives the power to hide in plain sight right in front of someone. That also lets him be completely broken as an adventurer since he can sneak up on things very easily, or just harvest plants while the big bad monsters can't even see him.
When he kills the bad guy, some girl notices the murder and tells him how to escape. But then she gets blamed as the culprit of the murder. Because he can't let his savior get imprisoned / executed for this, he rescues her...
If I'm remembering right, he does that rescue by figuring out where some knight / paladin person will be transporting her, figures out a good ambush point, and lots of other trickery from there, and I assume has to go and hide somewhere...