I am talking about this song. Entitled "Okonomiyaki" (お好み焼き), it is track 24 of Non Non Biyori Repeat's OST album, and appeared in Episode 8 (of the 2nd season) right before baby Ren-chon spilled the curry. It seems to have a certain quality that makes me think it's Russian. Considering that track 14 "Soft Dekopon" (ずいずいデコポン) of the same album is a traditional Japanese children's song ずいずいずっころばし, it is not hard for me to believe if "Okonomiyaki" is indeed based on some Russian folk song, but I am not familiar with those. So please allow me to ask this question here.