[Tangram]

I'm sorry, I don't know about Spain, but perhaps I could tell you what we in America are interested in? I imagine teenagers in the west in general have similar interests.

Talk about the mix of ancient and modern culture in Japan. My friends are fascinated when I explain to them that people still wear kimino in Japan, because they know it as the technology capital of the world.
That's another thing. It's common knowledge that Japan is a few years ahead of the rest of us, so talk about the latest technology over there. I saw a special about Japanese technology a few days ago, and saw people video conferencing on their cell phones. Like it was just perfectly normal, out and about in Tokyo. Teenagers love technology.
Music. Tell them about some of the most popular artists in Japan right now, and play a few samples. I've heard that foreign music is really popular in Spain.

That's all I can think of at the moment. Hope I helped some!