Board Thread:General BlazBlue discussion/@comment-32519675-20180120231613/@comment-30711988-20180121104619

I'm not quite sure if we ever got a proper answer for this question, but I think this is why Terumi and Hazama participated in the experiment:
 * As we know, Terumi couldn't merge with Hazama because of the Mind Eater, so he needed the Successor to Observe them as one. This Successor is Noel, the result of the Ibukido experiment.
 * The Successor knows the location of the Master Unit, and may be able to destroy or at least damage it as Kusanagi? Not sure about the last bit, but Continuum Shift shows that Kusanagi was indeed an important part of Terumi's plan.
 * Spiral Shift tells us about the coffin, which seemingly contains Izanami, but she can be awakened only when "fed" enough deaths. Both the Black Beast and the destruction of Ibukido with Takemikazuchi's blast result in a lot of deaths.