This version of Maxi 15, indicated by "Rev 1," represents a revised edition of the game released in the USA. The revision could include bug fixes, minor graphical improvements, or slight gameplay adjustments.  The nature of the changes made between the original and "Rev 1" version would be difficult to identify without access to both versions for comparison.  As an unlicensed title, the developers and the reasons for the revision are generally unknown.

Maxi 15 (USA) (Unl) (Rev 1)

Matsumoto Tooru no Kabushiki Hisshou Gaku 2 (Japan)