A Continuum Shift is when countless possibilities happen simultaneously and each one can become reality. The first Continuum Shift was caused by Noel Vermillion when she became the Successor of the Azure; it lasted between January 1st - January 7th, 2200AD. The second Continuum Shift was within the Embryo created by Izanami; it ended upon the descent of the Amaterasu Unit into the artificial landscape.
The first Continuum Shift occurred because of Noel's own insecure thoughts and inability to control her power as the new Successor of the Azure. It began immediately following the end of the Looping World and was Observed by the Takamagahara System so they could obtain the Azure. Each time a possibility occurred that they determined would not be in their favour, they used Phenomenon Intervention to change to another possibility with a higher likelihood of reaching the mystical power. Their powers allowed them to rewind time to an extent.
A Continuum Shift allows for possibilities that would normally never happen to become reality. Arakune was capable of besting Hakumen during one possibility, something that would ordinarily be nearly impossible.
The first Continuum Shift ended when Takamagahara was seized by Phantom and Yuuki Terumi as the AI's briefly stopped their Observation in order to watch Ragna the Bloodedge's victory over Terumi. Noel's thoughts had also collected by this time.
The second Continuum Shift occurred within the Embryo in the February of 2200AD. The Chosen had their memories altered and sought the Azure to make their wishes come true. Multiple possibilities occurred within the Embryo, but this Continuum Shift ended after Amaterasu entered the world and the Chosen's memories were restored.
A phenomenon that occurred when Noel Vermillion inherited the 'Azure.' Her insecure thoughts caused the world to fly off into multiple 'possibilities', causing 'Takamagahara' to take control of Observing the phenomenon.
The situation was actually favorable to Takamagahara, and using 'Yuuki Terumi;, who was immune to the phenomena fluctuations, they awakened the 12th Prime Field Device Noel Vermillion into the 'Sword of the Godslayer Kusanagi', and attempted to destroy the Master Unit Amaterasu to obtain the 'Azure'.
- BlazBlue: Central Fiction Official Material Collection, Chronology, pp.252-253
- BlazBlue: Continuum Shift, Story Mode, Hakumen - possibility
- BlazBlue: Continuum Shift, Story Mode, True Ending
- BlazBlue: Central Fiction, Arcade Mode, Act I
- BlazBlue: Central Fiction, Library Mode, Event #001