真しん祖そ

noun

true ancestor; original vampire

Used in fiction for a person magically transformed into a vampire, often as the progenitor of a vampire lineage. Not a common everyday word.

• その物もの語がたりでは、真しん祖そは闇やみの力ちからで吸きゅう血けつ鬼きに変かえられた。

  In that story, the true ancestor was turned into a vampire by dark magic.