Aldo no Isekai Tensei - Ch. 8 - Condensed Ray

[legendaryswordsman]

Yeah, it was never going to go any other way.


It's an inherently sketchy thing, which is why I would have preferred we sidestepped it. It's an argument that has no official answer because it's not a real thing that happens, but we can at least dig a little deeper than that argument.

Firstly, if mental age is irrelevant, that means any relationship with those childish-acting 900 year old lolis are clear-cut cases of pedophilia. Meanwhile, if a 50 year old man intentionally regresses his own body to 10 years old and romances another 10-year old, that's perfectly acceptable by your argument.
You can make that argument if you want, but I just want to point out that you are indeed making that argument.

Second, there's a difference between an age gap of 20 and 5 years old vs 40 and 25 years old vs 60 and 45 years old. The younger you are, the greater the gap in the ability to make informed consensual relationships, and that difference in dynamics is what makes age gaps problematic instead of just challenging. Someone mentally 90 but physically 30 can date another 30 year old just fine because they're both consenting adults at that point.

The problem arises when someone mentally mature enough to know the difference pursues someone they should know isn't capable of giving informed consent.

In regards to your examples:

1. A younger soul in an older body would be more ethically sound if they date someone their own age, but dating someone their own age is also less sketchy because as far as his partner knows they are simply two informed and consenting adults and he himself is incapable of making the mature judgement. In both cases, it's more sociological and practical issues to consider rather than ethics.
2. If an 8 year old body with an adult soul tried to start a relationship with someone the same mental age as herself the problem is no longer that there's an age gap because she can make the informed decision. The problem is anyone who would be interested in her at that physical age would be a pedophile by definition, even if they knew her true age.

The ideal scenario is really to wait for romantic parties to reach the physical maturing age, ideally before ever meeting or catching feelings early so it won't be at risk of grooming either.

Most isekai just have teenagers or adults reincarnated and go with people of their physical age. Most of time it's not an issue because author has way of making the reincarnated person act immature matching their physical age. Only time I really found it issue was musoko tensei or whatever is called. Where he brainwashed the elf girl to be dependent on him, it was done with intent, then Rudy with the relative, eventually though as with all storys when they physically mature becomes less of an issue.