(What, you don't have an iPhone?)
Emoji (Japanese emoticons, and these ones are very Japanese) are on your iPhone, but activating them, not so easy. I'm not sure what the technical details are behind all of this (I'm curious about it, but not so that I'm going to kill myself Googling), but I just did this on my 3GS and it works.
You need to get this (free) app and follow the directions. There are, apparently, other apps that work as well, so I assume the app makes a call (software call, not phonecall) to the Japanese emoji character set, so the phone then makes it available, but that's just a guess. Some of the emojicons are a little strange, but there are a lot of them. Make sure you use the "updated" number, not the one in the illustrations. No idea why you need to enter those numbers in that order, but it worked.
