It could be a story that focuses on the daily interactions, perhaps the growth of a unique bond, like shared secrets, small arguments, and the overall development of their relationship as stepsiblings over a period of time.
I'm not entirely sure as I haven't read it in full. But generally, it might be about the relationship and daily experiences between the protagonist and his stepsister. It could involve their growth together, how they deal with family dynamics, and the emotions that develop between them in this unique family situation.
I'm not well - informed about this novel, but it's obvious that one of the main characters would be the stepsister. And the other one would be the person whose perspective the story is told from, probably a male character who is now her stepbrother. They are the central figures around which the story would revolve in 'days with my stepsister light novel'.
Maybe there was a time when she participated in a school play. She could talk about the rehearsals, the costumes, and how nervous she was before going on stage. All these elements would make for a really engaging story.
If she has a more exotic pet like a hamster, she could have stories about building elaborate mazes for it or how it stores food in its little cheeks. These pet - related stories can be really heartwarming and interesting.
She once had the idea to make a large - scale family dinner. She started planning days in advance. She made a big pot of stew with all kinds of vegetables and tender meat. It was a warm and hearty meal that brought the whole family together around the table.
The unique premise makes it stand out. A relationship between ex - lovers who are now stepsiblings is not a common plot. It immediately grabs the reader's attention and makes them wonder how such a situation could even come about and how the characters will deal with it.