For anyone interested, I posted a brief description of the game’s prologue on its English Fanbase’s Facebook page.
The entire game takes place in the time span between Kotarou and the girls running simulations to find the answer to Kagari’s theory, and the final battle against Kashima Sakura’s familiars.
The game’s story is basically Kotarou trying out different possibilities and seeing how things would play out. For example, in the prologue, Kotarou knew everything early on.
The concept is quite interesting seeing how it could be considered canon.