Somany questions that having the hero be introduced open.
Does he only detect evil? Evil mosters specifically? Does the slime taking over a corpse turn her into a hybrid monster-human and is therefore not detected? Does the slime inherit the saint attribute and that overrides the monster attribute?
What about the couple dozen splits she had made to keep watch around her room/the mansion? Hero can clearly sense monsters that tiny so why hasn't he found the aplits she left? Are the splits also tiny little saints? Did the goddess intervene and made jelly something special? No way she can hide her slime nature from the goddess she is a saint of!
Aaah this new character can make for A LOT of really cool interesting developments!
Madam, your manservant has excessive chill. He's cool to the point of icy. Get him a plushy to hug or something.
Detect Monster, huh? Well, high senses. I wonder what qualifies as a monster. If Jelly is neutral and her aura is familiar, are her splits a monster or will Hero detect four saints? Is she a monster but not a monster because sainthood?
The funniest outcome to his ability to detect monsters would be that it has been going off over her this whole time and he's just ignoring it because "clearly it's just picking up on how much of a monster she used to be".
On one hand, it's good that he can't detect Jelly...
But on the other hand, it's kind of bad he can't detect Jelly... since Jelly clearly still has her little slimes around. If he can't even detect that, that's kind of worrying for her safety.