Poyiycu's feed

Wait, if Kurahashi was a descendant of Seimei, then who is Ranmaru talking about in this chapter?
https://www.mangago.zone/read-manga/youkai_gakkou_no_sensei_hajimemashita/mf/to_v-10-chapter-62/pg-12/
I thought he was referring to Kurahashi, but after reading this chapter, so its not him?
Ranmaru said that the person looked like someone he met when he was still in Takamagahara, around a thousand years ago. But if Kurahashi is a descendant of Seimei, he wouldn’t have been born yet at that time.