Tweetbot for Twitter – an upcoming Twitter client for the iPhone and iPod touch – is now available to download in the Japanese App Store.

The Twitter client has been expected for some time, and was previously in its beta version of development. However, it would appear that the app has been completed.

Developed by Tapbots – the same guys behind Convertbot and Pastebot – many believe Tweetbot could kill the official Twitter application, which lost a lot of support following the #dickbar incident. Beta testers have given the app very positive reviews, and we’re very excited to get our hands on it.

Once the app is available in the U.S. App Store, it will retail sell for $1.99 – you can expect the app to become available today (we’ll post once it’s in the U.S. App Store).

Here are some more screenshots: