One word could be 'prequel'. A prequel is something that comes before the main story and often provides the back story, like in the 'Star Wars' prequel movies which showed the events leading up to the original trilogy.
Another word might be 'antecedent'. It refers to something that comes before and can be used to describe the back story elements that are the precursors to the main events in a story. For example, the childhood experiences of a character can be the antecedent to their actions as an adult in the story.
Perhaps 'background'. It's a very general term but can be used to describe the back story. For instance, if a story is set in a post - apocalyptic world, the events that led to the apocalypse are part of the background or back story of that fictional setting. This gives context to the current situation in the story.
Chapter 408, ", Who Will Judge? Mr. Gu!", is the clearest early answer because it turns Rage Bear Legion's situation into a concrete plot event. Early on, There was one thing Blaywins and his comrades hadn't grasped.. By the end, What use was killing the witness?. Inside the broader technology upgrade storyline, the chapter closes with It wasn't too bad now; they still had the choice to break out on their own, even if it meant half of them might die—a chance nonetheless.
Chapter 431, ", I made the call too early.", is the clearest early answer because it turns Gu Hang's situation into a concrete plot event. The chapter turns that into something concrete by moving from Gu Hang received the news from Wu Jiarong on Shangyuan Star in the... to Even food supplies would be problematic; Upper Plateau Star probably....
Chapter 458, ", you dare too?", is the clearest early answer because it turns Alliance's situation into a concrete plot event. The chapter turns that into something concrete by moving from Could living on 600 Tax Currency a year starve him to death? to In the past, already a Planetary Governor, would he really have been.... What makes it stick is that the chapter closes with Still owe 59k, which gives you dare too a stronger narrative position and pushes the power growth onward.
Chapter 294, ", Murderous Intent Arises", is the clearest early answer because it turns Galaraldo's situation into a concrete plot event. The chapter gives readers a real answer by opening on Galaraldo also personally participated in the inspection. and ending on But even if they used impossibly high standards, they found no issues..
Chapter 434, "Title: Chapter 434, Assassination", is the clearest early answer because it turns Title's situation into a concrete plot event. It opens with The operatives hidden among the civilians weren't having much success... and closes on Confident in his skills though he was, Arno had not set up the bombs....
Chapter 354, ", Meritorious Unit", is the clearest early answer because it turns Meritorious Unit's situation into a concrete plot event. The setup is Currently, we are at this critical point., but the pressure keeps building through Gu Hang needs the human military to set foot in Fino City..
Chapter 412, ", Heaven and Earth Shatter", is the clearest early answer because it turns Green Skin's situation into a concrete plot event. It opens with Green Skin ships are terrible; they're terrible structurally, slow,... and closes on To the south lies the interior of the Eagle Horse Star Sector, and.... The key payoff is that the chapter closes with We're now at 74k...., which gives Green Skin a stronger narrative position and pushes the power growth onward.
Chapter 429, ", Battle Moon", is the clearest early answer because the buildup finally cashes out in a real clash. Early on, The Planetary Defense Force of Frost Origin IV had been consolidated;.... By the end, They had tried their hardest, but the real differences made the.... Inside the broader faction conflict storyline, the danger stops being abstract and the conflict around Battle Moon becomes immediate, forcing the surrounding cast to react under pressure.
Chapter 389, ", Capturing Planet", is the clearest early answer because it turns Interstellar Warriors's situation into a concrete plot event. A useful checkpoint is the way the scene starts with However, regardless of how many are willing to buy in, the internal... and follows through with I'll strive to settle it by February!.
Chapter 382, ", He Really Believed It!", is the clearest early answer because it turns Fatches's situation into a concrete plot event. The chapter gives readers a real answer by opening on Minnick had never contemplated seeking independence, but displaying a... and ending on They would polish it and add some evidence and data to corroborate.... In story terms, the chapter closes with If that Legion had always been stationed in the Fatches Tri-Star, he felt somewhat assured.