Grisaia no Rakuen, Prologue de la Grisaia?

[Murakumo]

I found an opening video under the name of Grisaia no Rakuen, with addition to title, "Prologue de la Grisaia". The video opening seems very different from the regular edition opening...I can;t seem to find anything on the net of a "Prologue" version; someone care to explain if this is fan made video or a part of an official product?


http://www.youtube.com/watch?v=m9H2HCVMl8U

 

[Animaksiat]

[MENTION=40274]lire711[/MENTION]; it's a sub scenario at Grisaia no Rakuen, after you finish it, the scenario will be unlocked