I was rewatching Sunred just now, and I thought that the voice of Miki, a colorful side character in ep.44, sounded familiar.

The show's page at ANN was useless, but fortunately the titles are easy to read: it was Sakura Nogawa. For a moment I imagined it could be Akiko Hasegawa, which would be pretty funny, and even went to look her up. It wasn't her, but here's something else: did you know that before giving voice to Miki (Hoshii), she made key animation for Porco Rosso? How's that for a career switch. Well, I mean, Naoko Yamazaki was a bit of a special case. So, what now? Tomocha?

P.S. Kurumi Mamiya was involved with Sunred before, and Makiko Nabei is the voice of Kayoko, of course (who does not appear in ep.44 otherwise). The wiki page for Mrs. Nogawa mentions a couple of other side characters that never grabbed my attention.