I'm not sure that a female JRPG main character is that conventional, is it?
I dunno, especially lately it seems like most of the JRPGs I see have main female characters, or at least prominent female cast members with a non-clearly defined main lead. Atelier and Neptunia come to mind, as well as FFXIII, obviously. I don't keep track of many popular JRPG series these days, though.
I can't nearly as easily think of JRPGs with male (or female!) leads in their 30s, 40s, or 50s. Generally high 20s for any character is pushing it, and if you
do go into the 30s or 40s, you're pretty much guaranteed to get a very stereotypical gruff and bearded trope-ish dude.
I dunno, those are just my experiences, and it was really just meant as an off-handed comment, since I was kind of like 'Whoa, are they seriously having someone like this as the main character? That kind of piques my interest!"