Of course it would be rare, but idols are normal people too so it wouldn't be surprising to see them eating with friends or shopping. Plus you see plenty of on location shoots for their tv programs. So have you or a friend met or seen an idol out in public? If so, how did it go?
There actually was a thread related to this in the AKB48 discussion section. But to answer your question, yes quite a few times... Matsuoka Yuki (AKB graduate): on the platform at Shinagawa Station Nakata Chisato: walking out of Wing Takanawa mall Imayoshi Megumi (SDN48) at an Izakaya in Hamamatsucho Ito Kana (SDN48) walking through Shibuya Ichikawa Miori/Takeuchi Miyu: getting out of a taxi in Akihabara Momoiro Clover Z (yes, the entire group minus Reni) standing outside Toyosu Station waiting for their manager to hail a taxi Iwasa Misaki (yes, I even ran into my oshimen) Crossing the street with her manager outside Hamamatsucho Station Matsui Sakiko: On the Yurakucho line heading toward Ikebukuro. In almost every situatin I didn't try to interact with the member. Although Imayoshi laughed when she saw us (I was with a bunch of SDN fans) and Chiichan smiled at me when she saw me. On the other hand, Momoka from Momoclo looked nervous when she saw me like she was afraid I was going to come over. In the case of Wasamin, she was incognito. But surprisingly her manager waved to me.
Oh, I'll have to try and find that thread then! And wow that's awesome! I don't know what I'd do if I saw my Oshi. I'd like to think to think I'd introduce myself, tell them I'm a fan, and go on my way, but I'm pretty sure I'd freeze up and just kind of glance from a distance trying to figure out if that's actually them haha.
Not an AKB member, but in 2008 (when I was studying abroad in Tokyo) I was with two friends in Shibuya at night inside this small clothing store, and we met Tanaka Kouki. I didn't want to say anything but one of my friends was a huuuuge KAT-TUN fan (I like them to but I only like Kamenashi), so she insisted we get a pic. We were the only ones who noticed him, and he seemed pretty unhappy about it lol. He didn't say anything and posed for the pic, but I felt kind of bad afterwards lolol
The thing is if you are in Japan you have probably met them at a handshake event. So the entire point of introducing oneself is pretty much moot. It is best to read the situation, and in my experience idols do want their space in public. There are exceptions of course.
Ah good point. Then again I don't live in Japan so I don't think I'd have another chance if I did see one on the street. I totally get reading the situation though. I've found most celebrities are fine with a, "Hi, nice to meet you. Love your work." and then going on your way if they're standing around, but if they're obviously in a hurry or going somewhere I've never tried to stop them.