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Spoiler for Response to Mentatsumi:

In the "Kyousuke Episode" when Kyousuke went back to the real world to delay the bus explosion, he saw Riki breaking off branches to make stretchers, and him and Rin started rescuing the classmates.

tl;dr: Kyousuke's vision was just Kyousuke's fantasy for best-case Riki & Rin. It was also a game-supplied walkthrough.

That was Kyousuke/Key's embedded walkthrough for 3-star bus survival. The steps Riki needs to take are word for word pretty much. You just had to transmit them to Riki when the time comes.

Kyousuke's vision of Riki and Rin being boss was merely his pipe dream during his route. In this pipe dream scenaio, Riki would need to be able to think on his own, and Rin would have to be able to maintain composure in the heat of the situation. He knew at the time neither Riki nor Rin was capable of doing so. Kyousuke never expected they would actually make his vision a reality. Hence at the end of his explanation of necessary actions, Kyousuke dismisses his selfish wish.

Riki's turn is supposedly the real world. Somehow, he and Rin get the reset button during the bad end, so there would be the divergence point if there were one. We're at least led to believe everyone is now saved in the real world. Not sure if Key would troll the heck out of players having all this contingent material for another fake world, but I won't rule out the possibility.