I seem to recognize these images from the artist's animation of the P3 drama CDs. I've found at least one of them subtitled on Youtube, but sadly that's all. The stories are interesting and the art just makes them better.
Wait, nooooooooo! I"m seeing images that look like they're from other manga, anime, games and whatnot. I see Code Geass, Kaiji, Akagi, Jojo, Death Note, Phoenix Wright, MGS, Evangelion, Pinocchio ....... my eyes....X_X
In response to all those 'flashback things', I think that this is just a self-made homage that segami daisuke made to show his thanks to his fans for two years or something.