You know, there's another magical girl who's outfit is based on her school uniform...
"Lyrical Magical!
I am the one who has been given a mission. Under the contract, release those powers unto me.
Winds to the sky,
stars to the heavens,
and the unyielding soul to this heart!
Magic to these hands!
Raising Heart, set up!"
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zeffy101 If there is a canon age difference, then if Vivio's age is around 20, then Nanoha is not older then 33. I wouldn't call her grandmother and I would say it's the best moment to have second/third child. And why shouldn't she give a birth to a child? Maybe Vivio is adopted and NanoFate want their own childe. I think there is fanfic with similar situation.