What to talk about when teaching about J-pop culture?????

I really want to try helping you out, so...
I think it's a good idea to talk about Vocaloid, just explain how the software works (how people record their voices) and how technology is advanced in Japan. Since it's about pop culture, you can also talk about whatever's trending in Japan. Talk about fashion, music, etc.

This has a list of things that are popular forms of entertainment in Japan (which includes anime): link
If you just want to talk about anime in general, I guess you're going to have to explain how it was created first. Then you can talk about the impact, how there are people all over the world who like anime. Explain anything you know about anime culture, like cosplay and conventions maybe.

I'm not very good at giving advice and everything, but I hope that I at least helped you get a little idea. '^^

If your interested another really cool thing to do would be to talk about Japanese pop culture fashion (lolita, Visual KEI) and cosplay of course :)

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I myself have done presentations on the Vocaloid programs in the past at my school, it might be really cool to show a concert clip and the idea that their not real but people love them anyway. (I could literally go on all day about giving presentations about vocaloid, if you want more just ask) I would also talk about conventions, a good one to bring up would be comiket as it's know for being the largest dojinshi expo.

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another cool thing with conventions would be to bring up any in your area. In general anime wise I would bring up the start of it and the art style itself and that it's popularity is not only in Japan and the U.S but across the world as well.