One great fanfic could be one that focuses on exploring the side characters more deeply. For example, a fanfic that delves into the backstory of Hajime's classmates and how they adapt to the new world without his initial presence. It can add more layers to the story.
Well, being the star in Project Sekai's story means facing unique challenges and having the chance to shine. You get to make important decisions and shape the outcome of the story.
Shinjo Masayuki was a Japanese manga that told the story of Shinjo Masayuki, a high school student with magical abilities. After he accidentally obtained the ability to freely manipulate water, he had various encounters with various characters in school and in his daily life. The manga was released in 2009 and is still being released.
Well, 'sekai no owari no encore light novel' could potentially have a unique and engaging story. It might explore various concepts like survival in a post - apocalyptic world, the relationships between characters during such extreme times, and perhaps some sort of redemptive or discovery journey. But again, this is all speculation without further knowledge of the actual content.