In which episode of Sailor Moon S did Kaiou Michiru (Sailor Neptune) and Chiba Mamoru (Tuxedo Kamen) meet each other in civilian form for the first time?
Note: I don't recall any earlier points where Michiru and Mamoru interact in civilian form, and I've been keeping an eye out for this since I started watching this season a week ago. It's possible I may have missed something though.
In episode 4 of Sailor Moon S, Michiru and Haruka observe Mamoru from a distance during and after the concert. (They are sitting some distance away from the five "confirmed" Sailor Guardians and Tuxedo Mask, and they have opera glasses. Haruka points out Usagi and her boyfriend, whom Usagi had been complaining of feeling inadequate for, to Michiru.)
In the beginning of episode 9, Mamoru explicitly interacts with Michiru. He has gone with Usagi and the other girls to watch Haruka at a motorcycle race. After the race, Usagi talks to Haruka and Michiru, bringing her friends and Mamoru. (It's worth noting, however, that there is no introduction---"This is Mamoru; this is Haruka and Michiru"---in this episode. Either the introduction is simply handwaved, or they were introduced at an earlier point, before they are shown explicitly interacting for the first time.)