DJMax Portable Black Square (Korean: 디제이맥스 포터블 블랙 스퀘어, dijeimaegseu poteobeul beullaeg seukweeo; abbr.

The original aim was to launch the game in November, however due to numerous bugs or piracy issues[2] with DJMax Portable Clazziquai Edition, the release of DJMax Portable Black Square was postponed.

The music starts playing again when the next special note is hit, and the extra points are reset to 1000.

Players can use Link Disc feature with DJMax Portable Clazziquai Edition, allowing them to play the songs of Clazziquai Edition along with song patterns and RD patterns unique to Black Square.

Link Disc with DJMax Portable 1 and 2 is also possible but only unlocks avatars, songs, notes, and gears for Black Square.

Black Square is the fourth title in the DJMax series and the name for this special package is derived from Italian word "Quattro" which means number "four".

It contains a retail version of the DJMax Portable Black Square PSP game, an original soundtrack which consists of four audio CDs, an art book called Illusion: DJMAX Metro Project Visualization Book containing notes about the development of the game, graphical art and credits with pictures of every developer.

The package also has small portable speakers, a Black Square themed bandana, a 2009 new year's card, and a Son of Sun Special Gift which consists of plant seeds and a cup.