You're exaggerating. Plus NTR is when they are in a relationship, which they aren't. Also Ran doesn't seem she likes either Saki or Keiko's ex in that way. Are you per chance drunk? (slightly joking)
no dude, sober.(never been actually drunk if you ask me)
god, what i've started... seems that ntr is a kind of magical phrase on this site: whenever someone spills it out - here is when the outburst commences! that post actually meant to be marked with /jk/ - sorry i forgot. (but again, you never know what awaits us around the corner, especially with Higashiyama )
anyways, pretty curious chapter, as in could be a lead-up to some arc closures. i'm suggesting Keiko-sempai's mother - arc and that whole past that's haunting on our black-haired stretching main character, just speculating here though