Only if they have the same base class. Example: Hinoka and Subaki are both Pegasus Warrior, so when they marry, Hinoka gets Subaki's secondary, which is Samurai, and Subaki gets Hinoka's secondary, Lance Fighter.
I really don't want to factor in growths since most units in this game have good growths and they're mostly irrelevant for min-maxing(unless you do something obnoxious like make Midoriko a magic unit). Plus, I don't even know why Mitama wants to be a Basara when an S-rank class is much better(unless it's Sorcerer).
Mitama can A+ Kanna(pick Fighter as your secondary) or marry her yourself(not a problem since Mitama has amazing modifiers).