Yes, unfortunately, Hange met their end in the manga. It was a poignant moment for fans. The circumstances leading to their death were quite intense and had a significant impact on the story.
In a post - apocalyptic fictional story, there could be a group of survivors who get stomach rumbling and diarrhea after eating some contaminated food they found. This would be a big problem as they are already in a difficult situation. Some of them might think it's a new virus or something, while others would be more concerned about finding clean water and proper medicine. It would create a lot of internal conflict within the group and also make them more vulnerable to outside threats.
Well, in a fictional adventure story, a traveler in a strange land could get stomach rumbling and diarrhea from eating an unknown fruit. This would then lead to a series of events like seeking help from the local tribes, who may or may not be friendly, and it could be a turning point in the story, either making new allies or facing new enemies.
I'm not entirely sure as I haven't read it in detail. But generally, a visual novel often involves a story with characters, plot twists, and multiple endings. 'Rumbling Heart' might be about relationships, emotions, or personal growth of the characters in the story.