On June 1, 2007, Little Busters! Trial Edition was made available for download over the internet. A physical version was also produced, rumored to have been obtainable by people visiting Visual Arts's headquarters around that time. This appears to be the only way the physical Trial Edition could be obtained, though this claim is yet to be verified.
The disc image is viewable here: https://i.imgur.com/tdskk16.jpg
Three days later on June 4, 2007, Trial Edition Ver1.01 was released for download over the internet, while Ver1.00 was removed. It is unknown if this update had an effect on the physical disc's distribution.