@sundowner I see, thanks for replying. They seem too clean to be scanned from physical pages, though, so I'm hoping that maybe the magazines are at least available digitally. Do you maybe know if older Harta volumes (starting from Feb 2013) are available digitally?

Self-answering and accepting own answers to own questions is completely fine and isn't against the rules.

1. Others may have different interpretation or there may have been details we missed but I think this is correct. Advice: in future answers, try to elaborate and provide references, if possible. 2. Yes. I meant to say family name or the last name.

The question is asking who Miku is talking to. Your answer is talking about a guess on what happened in the episode and did not mention who Miku was talking to. Please clarify what you really wanted to know. What I think happened: it was Ichika that Miku was talking to due to the fact that she called the MC by his first name during the call (Itsuki calls him by his given name). Manga is a bit unclear but in the anime, it showed that Ichika was outside when Miku made the call. When she went out, when she went back in, it was not really mentioned.

Just to confirm: did you watch this episode and the next without skipping anything? If yes, then I am not sure how this information was missed. If not, I suggest re-watching the episodes. Did you also try looking this up or maybe checking the manga?