Sorry, everyone. I just think those names should be for Japan only. I don't know about "Riku", but "Sora" and Kairi" sound a bit American to me. Maybe we can leave Riku Japanese, as I could figure that he's at least half-Japanese, but Sora and Kairi look more American to me. We pronounce the names in an Anglicized manner, meaning that we take a name from another language and make it an English name. When you anglicize a word, it becomes English. I learned that from Wikipedia. So maybe we CAN give Riku a Japanese last name, assuming that he is half-Japanese, but "Sora" and "Kairi" sound more American to me. When you give a Japanese last name, though, don't make it sound too Japanese. It has to be a name that Americans can understand.
Face it, SM. Sora, Riku and Kairi are Japanese names, and they were meant to be Japanese. Also, don't believe everything Wikipedia says, it's not completely accurate. And stop trying to twist everything to make yourself right. You're allowed your own opinion, but it's wrong.
Then why did they name the Twilight Town kids Hayner, Pence, and Olette? Those names sound American to me.