I'm not sure specifically what the'sama sama letter day story' is about as it's not a widely known common story. It could be a very personal or a story from a specific local or cultural context.
The Kaguya-sama manga is indeed finished. It ended after a successful run, leaving fans with memories of an engaging and enjoyable story. The final chapters tied up loose ends and delivered a conclusive ending.
Yes. The Kaguya-sama manga has reached its conclusion. It provided a satisfying ending for fans. The creator wrapped up the plotlines and characters' arcs neatly.
They could be original characters created by the fanfiction writer. Just two fictional people with their own personalities and backstories that the writer has developed specifically for this story.
She could also be a symbol of a larger group. Perhaps Annie represents all the women or a specific ethnic group who have faced systemic discrimination. The 'justice for Annie' campaign, based on her true story, could be a way to highlight the broader issues of inequality and fight for justice not just for her as an individual, but for the whole group she stands for.