@Banshie
*did some edits*
I... dont think it was ever mentioned the legal age in the isekai world.
In the real world however the legal age for sex in japan is alot lower then most countries.
16 is usually consiferd the more "tastefull" limit, but striktly legaly speaking you can have sex with people of age 13 and above if they agree to it.
So no, but also yes depending on where in the world you are.
The #age of consent# as its usually referd to changes from 21 all the way down to 9
Now that said, you can also be legaly able to have sex and still be a minor in some of those places.
Being a minor is not always based on the age of consent, but can also for example be based on the age of drinking or the age of when you are legally allowed to live on your own.