Well, generally speaking, if it's a visual novel about 'big chest vs flat chest' in a non - inappropriate way, it could be exploring concepts like body image, self - acceptance, and the different experiences or stereotypes associated with different body types in a fictional story world. Maybe it shows characters with these different body types interacting and dealing with various situations, but again, this is all just guesswork.
I would say no. The title alone implies a comparison based on body parts which is not a concept that is typically considered appropriate for all ages. There could be elements of objectification or inappropriate content within the visual novel that would make it unsuitable for younger viewers or those who prefer more family - friendly media.
I'm not sure specifically which 'call her daddy' story you mean that's non - sexual. But there could be a story where a little girl calls her father 'daddy' and they go on an adventure in the forest together. They might discover a hidden stream, and daddy shows her how to skip stones on it.
I'm not sure if there is a specific established 'Flat Earth Sex Story' in a common sense. It could be something very niche or made - up. If it's not a well - known or mainstream idea, it's likely fictional.