nojojojo mentions "...the protagonist (who) looks like a ten-year-old girl, even though she's actually 53 and a kind of adolescent in her species' terms" and as Flow would have it I've been considering 12 Kingdoms' King of Kyou, the little girl who wishes she had a shorter kirin, the more easily to slap him when so minded. The King of Kyou is twelve and has been king for 40 years or so, meaning that in terms of actual experience she's in her 50s too. Now kings are necessarily childless after they become kings, but one wonders if a prepubescent might not want to be an adult at some time in her theoretically endless life. Adults can have sex, and I never heard that Kings couldn't. You'd think she might ask to be removed from the rolls for, say, six years, in order to reach maturity.
I was going to say, she might want to forgo adolescence if she was facing an eternity of menstruation every month. I would, for sure. But since babies grow on trees in that world, presumably all human fertility functions are suspended. Including, possibly, sex itself. I wonder if the novels ever address that point?
(It's a nice settei and all, babies growing on trees, but the far-reaching implications are that there's no need for human sexuality, hence for sexual division, so why do we have sexes? And why do men have beards and deep voices, the result of the hormones needed to turn them into procreative beings, if they don't procreate?)
And I wonder how much the physical changes of puberty are necessary for emotional maturity? Would someone who remains physically twelve for half a century nonetheless mature through experience, or would they stay a child? The King of Kyou is a tough-minded pragmatist whom I would peg as a mature 25 or so, but there's nothing middle-aged about her that I can see.