Ensemble Stars! is the first installment of the series, spanning from the start of the school year in spring until graduation, ending with EP:Link. It covers the cast's time in Yumenosaki Academy.
Ensemble Stars!! is the second installment of the series, which takes place after EP:Link. Many characters have moved up a year or graduated, and now continue their idol activities as members of Ensemble Square, an entertainment agency, and introduces additional units. All characters from Ensemble Stars! are still featured and no units have broken up.
When starting Ensemble Stars series, players can begin by reading Main Story or by reading the other story elements (events/scouts, sub stories, or even mini events) and return to Main Story later. Likewise, players can also choose to read other story elements between each main story installment.
For those who have already viewed Main Story once, here is a refresher on the basic premise of Main Story and its outcome, as well as how it links to Kiseki Series; it is not recommended you read this blurb if you have not already finished Main Story:
Main Story Spoilers
Yumenosaki's environment grew stifled under the student council's rule, and freedom of expression was discouraged. While Yumenosaki produced excellent idols, idols who did not abide by the school's vision of what a "good" idol was would ultimately score so low they would be forced to leave school.
Trickstar defeats fine, the school's top unit led by the student council president, Eichi Tenshouin, in the DDD, which is a special DreamFes. This effectively ends the student council's reign over the students. Students are now free to express themselves and perform as they wish, and Eichi, moved by Trickstar's "miracle," says he would like to see what this new future has in store.
By winning the DDD, Trickstar is now eligible to participate in the SS, a nation-wide idol competition. In the coming months, Trickstar will now have to prepare to represent their school on the national idol stage.
Kiseki Series covers the months leading up to the SS, as well as the SS itself.