So are there going to be another isekaiers down the line? Could be interesting if done well or more likely you will have them as the antagonists. Some brats going all entitled now that they are the "chosen ones" or something.
Why would it shine when answering yes to if they were male and if they were resident of the world.
If the detector worked based on the body it would not shine when asked if they were a resident. And if it worked based on the soul/spirit it would not shine when asked if they were a male.
I'm guessing the question would have to be
were you male or
have you always been female for it to not beep and currently the MC is the character in body and etheric... body? soul?, who has always been female. Further proof is how
her backstory was found out to be the truth and not his. Likewise, she is not a resident of this world, but that of some game (world) and now is here.
So essentially, it takes out "her" truths that the MC wrote out when he designed and played out the character, but not his. So while most likely 100% accurate with beings of this world, but when it comes to transmigrators, it is only accurate on their current form and not whatever they used to be.
A more interesting question is, how would it work on say the possession type transmigration, where the isekaier takes over someone who already existed in the world? Would it detect that their etheric truths have changed around or would the person still have the same "lived experiences" as before, but with just different person in the control seat? Hell, how would it work if this world has some possessing demons or spirits around? Would it detect them or could they pass detection as long as they can access their hosts memories and aren't caught in a lie recorded in the etheric body? Even in our MC's case I wonder how it would beep if they asked the right questions. For example "were you always Susy?" or something. But I doubt these two even have any inkling that this could happen, even if they have historical proof of transmigrators.
Now we just wait for some amount of chapters to pass and for everyone to forget about this technology, when there is some crime mystery whatnot going on and having an essentially near accurate lie detector around would be
incredibly convenient...