An old unnamed man and woman who wear masks during their appearances in the manga.
The old woman sporting a witch's hat with a surgical mask and large sunglasses, and the old man in an apron with a hockey mask
They lived with their children in a rural area in The Magic User World, living a modest life without any worries, they seemed to be affectionate and supporting to their kids, and showing pride at Kawajiri for been choose to become a Devil.
Thanks to Nikaido repetitive interference in the past in hopes to change Yakumo's fate (killed accidentally when the young girl went back in time) the couple never met any of their children, Yakumo was dead, and Kawajiri was raised in an orphanage, leaving them completely alone
When Nikaido fully mastered her magic, she went back in time in order to save Yakumo, in an estrange way, with a little help, the baby Yakumo was able to change her own fate by flying directly to the couple, as they were camping near. And thus, they became Yakumo parents, raising her as their only daughter.