Well the picture I deleted didn't really have the best quality, nor could one tell what was going on in it clearly. Also on the note, please name the files to something understandable, not having random letters and numbers jumbled together.
I know in the past we discussed and agreed on not referring to his characters as Salaryman Yamada in the episode cast lists, but I think we should make an exception for the 2018 anime. By now Numata is a bonafide recurring cast member and I believe he should be credited as such. And unless we note that he's Salaryman Yamada each time, it's gonna look to outsiders like several random one-time characters are for some reason listed as recurring.
I'm alright with refering to him in the episodes' cast lists, since there's also the character section that's already has the link to the salaryman yamada page whenever he appears. (The [character] (Salaryman Yamada))
I don't have time right now to research which kid is which by listening to other roles by the two voice actresses (which is what I did for the Shuichi Yamada cop and the new 2018 VA info I recently added for Salaryman Yamada), but I was able to confirm the historian is Katsumi. Why he got a name is unclear, though he does kind of resemble real life yokai researcher and Mizuki friend Katsumi Tada.
"oitekebori" the phrase means "abandon someone", but the kanji for "bori" in her name 堀 means "canal", so I guess her name means something like "person who drowned in the canal", but I can't think of a short, punchy way of saying that other than "Victim of the Canal" (which I'm not particularly happy with)