ty for lmk!! i'm gonna go in and fix that 🙇The genitive for “Miharu and I” is “Miharu's and my” (or, for the absolute, “Miharu's and mine”).
“I's” isn't a word, and every noun, pronoun, or name in a joint genitive needs to be its genitive form.
you're right but also "all over the country" kinda means the same thing as what nationals are and sounds less awkward in the dialogue (to me at least, if it's confusing for others i'll totes change it)全国 should be "nationals" here. Short for something like 全国大会 (I have no idea if track and field/sprinting has some specific national meet/tournament with a name).