If you're jailbroken, just lookup "Emoji" in Cydia. It's a free work around. If you're not jailbroken, just open the app store and search emoji. There's a bunch of 99 cent apps to enable emoji.
Whatever program you use to enable the keyboard, afterwards go into Settings -> General -> Keyboards -> International Keyboards -> Japan. There will be a toggle for Emoji. Turn it on and you're done.
Be aware, it only works on other iPhones. It appears as little squares, or random gibberish characters everywhere else.
For example: here's a smiley face. If you look at this page on an iPhone, you'll see the emoji.