The game is set after the events of BlazBlue: Calamity Trigger. A few days have passed since the reported raid by Ragna the Bloodedge, The 13th Hierarchical City "Kagutsuchi" forgets to celebrate New Years, as his alleged involvement in the "Mysterious Bombing" and "Huge Pentacle Sightings" becomes the talk of the town. With the NOL offering no official explanation, the citizens voice their own theories, exaggerating and spreading rumors like wildfire. Completely indifferent to the state of the city, Ragna grips his massive sword and quietly bides his time—waiting for the chance to achieve his true objective, and then, the enormous "power" that has ensnared Ragna begins to activate...

BlazBlue: Continuum Shift Extend (originally titled BlazBlue: Continuum Shift II Plus) was announced for the PlayStation Vita at E3 2011, and was later confirmed to be slated for the PlayStation 3 and Xbox 360 as well. The game features an updated version of Calamity Trigger's Story Mode called Blazblue Calamity Trigger Reconstruction; the inclusion of Relius Clover as a playable character; four new stories for Platinum, Makoto, Valkenhayn, and Relius; a new Unlimited Mars game mode; hidden Distortion Drives for every playable character's Unlimited form; and further balance tweaks. In addition, the game also includes a new opening animation produced by Production I.G. as well as new theme song called "Sokyu no Hikari" (???? Celestial Light?) by Faylan.[6] Aksys has also released Continuum Shift Extend internationally.
A version for the game for the PlayStation Portable was released on May 31, 2012 in Japan. This version features an exclusive BBQ (BlazBlue Quiz) Mode not found in the other versions. However, while the other versions have full online play, the PSP version is limited to ad-hoc, with support for two to four players. On November 14, 2014, it was confirmed by Korean studio H2 Interactive that the game would be receiving a port to Valve Corporation's digital store, Steam, to be released on December 11, 2014 with online play intact, unlike the Steam port of Calamity Trigger which had the netplay removed possibly due to the game's usage of Games for Windows – Live.