I don't believe so as Mikoto and Hakuro/Iceman only had one child while Eruru has her little sister Aruru. remember that the pact between Eruru and Utawarerumono was to save the life of her little sister Aruru who had just been killed during an earthquake1
However the Ring Eruru has is indeed the same same Hakuro gave to Mikoto as it is shown to have the same id credentials to access the research facility so it is more than likely Eruru and Aruru are decedents of Mikoto's and Hakuro's baby.
Also keep in mind that the Mecha used by Kuuya's Kingdom are the same as the ones the humans from the research facility used to survive outside and Kuuya's Kingdom seems to have been around for a while so i would suspect that a very long time has passed since Hakuro went ballistic in the research facility and turned all the humans in there into blobs. otherwise it's far too short of time for Mikoto's baby to reach Eruru's age while at the same span of time Kuuya's Kingdom are given the ability to use the Mecha and become one of the dominate forces on the continent
1: i think it was an earthquake which killed Aruru however i can't exactly remember. however i do remember from the visual novel it being revealed that Utawarerumono (or at least Hakuro) had appeared before Eruru and in exchnage for Aruru being revived Eruru was to become faithful to Hakuro which led him to question her love for him. she however ensures that she does love him herself and not because of the pact she made