This is why I gave the reminder:
Only part of that comment was me not caring about your wonky napkin math-- the other part was calling your napkin math wonky.
It's wonky because it assumes her maturation is linear, even though we're told that it's not linear and even though you acknowledge that it isn't linear to begin with. It's wonky because if her having lived for
27 years means nothing in any dimension of maturity, then elves are naturally mentally deficient relative to humans in this world and it doesn't even matter when she reaches physical maturity.
You're also confounding biological and social factors (they're
related, to be sure) in modern reality by talking about the beginning of puberty on one hand and then discussing the age of adulthood in Japan (despite this being a fantasy manga) on the other hand, without even engaging with the history of the age of adulthood across space and time and what made people to be considered "adults" at any stretch in premodern times. There were cultures that considered you "adult enough" at 15 if you were a woman, or considered you "adult enough" at 14 if you were male-- there were cultures that considered you "adult enough"
at your menarche. All of these cultures knew you weren't "fully mature" at those ages, too, and considered part of "early adulthood" to involve "getting your bad impulses out your system so you could be a functional full member of society" (if you were male, at least).
What are the standards of this world? What do they even matter, for the purposes of this story?
With so little development of this factor thus far, I'm not going to bother even trying to rack my brain about the age of adulthood and consent in this pseudo-medieval fantasy world until Dion starts waving around his
Rechter Zeigefinger des Drachen at this elf that's lived for 27 years (or alternatively, she starts craving human flesh)
. Until then, I also find your napkin math unconvincing
regardless of whether or not we should be calling her a "legal loli".