Oh my god! It was Kyousuke all along! How could we have ever seen it coming?? But we still have the question of why he did it. Well, sort of. We know quite a bit now. Apparently, he was trying to force Rin to grow up because everyone would disappear. But we still don’t quite know how they will disappear and why he was able to orchestrate it all.
Presumably, it’s alternate timeline-related, considering how he could predict things before they happened. But has he now disappeared himself? Nearly all members of Little Busters have disappeared, so what else is left to do in this show? Sounds like a lot of episodes with Riki alone in despair would be soon to come.