
Try reading it again. Kurahashi wasn't even there. The one wearing the black undergarment is Ren. Yanagida, Rensuke, Sano and Momonayana are the only students in that scene. Principal already knows it's Sano that Ranmaru is referring to bec in the earlier chapters it was already mentioned that Sano is not a youkai but a God

just because kurahashi didnt appear in the chapter doesnt mean hes not there. at first i thought it was sano too, but they wearing different clothes.
https://www.mangago.zone/read-manga/youkai_gakkou_no_sensei_hajimemashita/mf/to_v-10-chapter-62/pg-12/
idk bruwh, i mean yeah the principal looks like he knew something

Oh it got sent whilst not completing it haha sorry. Well I think our disconnect is because I have another theory of who Kurahashi and Sano is. First, Ranmaru isnt aware of Sano's true identity. I can't really say for the principal though. My theory is Sano is the Susanoo no Mikoto and Kurahashi is from the Kurahashi clan (specifically Kurahashi Yasuyoshi) - a branch family of the Tsuchimikado clan which are decendants of Abe no Seimei that's why I'm certain he is referring to Sano and not Kurahashi. If Sano is indeed Susanoo that would explain why Ranmaru feels he saw him whilst he was still in the Land of Gods. If the basis is because Ranmaru is looking for the "spy student" from class 2-3 it would really be understandable if he would think that person is what he saw from the land of gods because Ebisu is a God and the person would accompany him might also be a God.
I've seen like forums and they also have the same opinion as yours but yk let's just wait and see? hehehe
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.