>>14570151
>Certainly not the normal fox we know in real life
Actually, the fox youkai isn't fundamentally considered any different from a regular fox. Any fox that lives long enough should, according to the folklore, gain magical powers and superhuman intelligence as well as the ability to take human form. Therefore it can be assumed that barring the mentioned upgrades they have the characteristics of regular fox, as it is supposed to be the animal itself at a spiritually enlightened age as opposed to a folklore character that is a distinct version of the animal.
And besides that, since they only gain the ability to take human form after living at least several decades, longer than any real fox has been observed to live, but are still reported to have bore children with humans, it must be presumed that they maintain fertility into old age, though that may be a function of their spiritual nature rather than the fox's lack of menopause. That said, menopause isn't particularly common in non-primates, and while sexual senescence is exhibited by most animals that live past prime breeding age, it is usually characterized by a drop in fertility rather than a complete stop.
Basically, Ran is a fox so you can still get her pregnant.