I'm not entirely sure. There may be a novel out there with 'Red Kobayashi Hiromi' in it. It could be a work by an independent author or from a particular genre that isn't widely known. Maybe it's a mystery novel where Red Kobayashi Hiromi is the detective, or perhaps a romance where they are the main love interest. Without further details, it's all speculation.
Another great 'higuruma fanfic' is 'Higuruma and the Mysterious Case'. In this one, he gets involved in a complex mystery that tests his skills and beliefs, and the plot twists are really engaging.
Typical characters can be ordinary people. Maybe a middle - aged woman trying to find her place in society or a young man struggling with his career choices.
Common themes often include human relationships. For example, the complex interactions between friends, family members or lovers. Another theme could be self - discovery, where characters learn more about themselves through various experiences.