Though, that theory comes back to bite me with the start of the manga as to why would prince hans try to hide the fact the princess is dead knowing the instability it would cause besides the literal blood on his hands. Unless this is not the original prince hans, I’ll just guess things didn’t play out right with our assassin, as he put up a stunt of bravery he had killed the princess with a piece of furniture rather than the assassin’s blade. Or actually maybe it’s his parents doing all of this, they’ve arranged the marriage and stuff, they might as well send an assassin under their son’s name as to not directly link to them should it fail.