A sandwich novel is a form of literary work. It often consists of different narrative layers. The 'filling' part is the core of the story, around which there are other elements that add depth and complexity. It's like a sandwich where the main ingredient is the focus, but the bread and other toppings enhance the overall taste. In a sandwich novel, the outer 'layers' might introduce characters or situations that lead into the main story and also tie up loose ends after the main plot has been told.
The sandwich is said to have originated from John Montagu, the 4th Earl of Sandwich. He was a gambler who didn't want to leave the gaming table to have a meal. So, he asked his servants to put meat between two slices of bread. This convenient way of eating soon became popular and was named after him.
A 'sandwich story' could refer to a narrative structure where a central event or idea is surrounded or sandwiched between other related elements or plotlines.
I'm not sure specifically as I haven't read it. It could be about various things like a story set in shiny or bright days, perhaps a coming - of - age story where the sunny days play a symbolic role in the characters' growth.
I don't know who the author of 'Shiny Days Novel' is. There are so many novels out there, and without more information, it's hard to determine the author.