I'll answer both
The AH story takes place where Imperial Japan in WW2 was able to scrounge enough resources to make Operation Cherry Blossoms at Night / Operation PX possible, which is a two part plan. Part 1 is to drop specially made bombshell that contain fleas with the Bubonic Plague but also contain the lesser known but deadlier sister the Pneumonic Plague to infect the US. Part 2 was using long distance balloons to drop anthrax on farms to infect livestock and crops.
While not a game changer for Japan the events spurred forth an alternate ending for WW2. Won't spoil more but I will also has cherish the chapter about Operation Frankenstein, fictional but I wish it happened. Other than that it's how people were decent to each other in spite of all the horror happening.
I need more information on Fate/Type Redline to consider a proper draft. The story is moving too slow.
Well Redline has most of what happens in the story but I've changed the background for an alternate history darker WW2 that still had the same outcome but with a higher body count. Takes elements from the above story and The New Order Last Days of Europe, a Hearts of Iron mod known for its intricate plot and mostly well researched history.
The AU takes place in a different world line from my main Trust Sign story which has yet to be made due to my schedule, there a alternate version of my protagonist Hikaru (different last name) knowing gets himself involved with the Grail War but ends up with the second Saber, his grand father Hajime Saito, with a theme of hated this Hikaru has so much loathing for his home and the world because of the war that he becomes an constant obstacle for Arata the Redline protagonist as their views and motives clash.
Plus I wonder with how much period accurate racism I am allowed because of how all the different people involved see each other, like the internal struggles of Japan also the Nazis. And I'm not holding back on the darkest villains that do appear alongside Major Magatsu as ensemble antagonists, Shirou Ishii who you will learn about in the AH story, and survivors of the Dirlewagner Brigade one of the worst group of war criminals in history, I'd advise not to read about either of them after eating.
I would have brief excerpts of world building with history books and such to describe what's going on and how this WW2 is different from our own.
While it would not be covered in my comic save for brief adaptions I'm doing a fanfic.