I don't actually know more than Wikipedia tells me, and it's been suggested that the yamanba may have been Kintarou's step-mom, but regardless of the blood relationship, she raised him.
And now that we have translation, it seems to be implying that this is actually the yamanba that raised Kintarou - but the fact that Mao-chan and Yamanba are having a tender moment means that Reiga can't ask if it's true right now.
Wait, does that mean we'll see Shuten and Ibaraki??
Wrong mountain. Mt. Ashigara is where Sakata Kintoki (childhood name: Kintarou) grew up. Mt. Ooe is where Ibaraki and Shuten's Oni gang dwelled.
Hang on, bear...?!Yamabaa...I'll just bribe her!Mao!
I'll be givin' ye my wee one's old things!The Truth Lies Within MemoriesThe Mountain Witch... has kids...?Hmm?This is totally not the right kind of atmosphere to be asking about the whole "Kintarou" thing, is it...It suits ye right down to the ground!My, this brings me right back...Cheer up!Mao...?Kintarou...Are ye comforting me?I'm right chuffed!An axe and bib!This bearskin is from the bear that my wee one often had sumo bouts with, too...That Kintarou...?