Haiyore! Nyaruko-san/WMG

The Yasakas are related to Old Man Henderson
Nyarko muses in Episode 3 if Miharo is related "to the cursed deity hunter in the black book!?" His mother is able to take on Mythos deities using just forks. They're able to communicate and live with Nyarlathotep, Cthugha, Cthulhu, AND Hastur, and still not go insane.

There's only one person that could do this: a man cursed with insanity, and actually destroyed Hastur. The only answer is that Miharo and Yoriko is decended from Old Man Henderson - The Man Who Won Call of Cthulhu.