There might be a mentor - like character. This could be an old and wise cook or a magical being who has extensive knowledge about the rare and special foods in the different worlds. They would guide the main character on their journey to discover new ingredients and recipes. And there could also be antagonists, perhaps those who hoard the rare ingredients or try to stop the main character from spreading the knowledge of certain powerful foods.
In many 'gourmet in a different world light novel' stories, the main character is someone who is passionate about food. They might be a professional chef in their original world or just an enthusiastic amateur. Alongside them, there could be a guide - like a native of the different world who knows the ins and outs of the local food scene. There may also be rivals or friends who join the main character on their culinary adventures in the different world.
I'm not sure exactly who the main characters are in 'the gourmet gamer novel' as I haven't read it thoroughly. But it's likely that there's a gamer who is really into food, that's probably the main character.
The most interesting part might be the creativity in food descriptions. 'Gourmet in different world novel' could describe the taste, texture, and appearance of the foods in a very vivid way. It might make the readers feel like they are actually tasting the dishes. For instance, it could describe a dessert as having a silky smooth texture like a cloud, with a sweet taste that explodes in your mouth like a burst of magic. And the settings where the food is prepared and consumed are also fascinating. It could be in a grand castle kitchen or in a small, cozy tavern in a hidden forest village.
There could also be characters in the new world who act as friends or foes to the main character. Maybe there's a wise old man in the new world who becomes a mentor - not in the Naruto - style but still gives useful advice. And of course, there might be antagonists who oppose the main character's rise with the Naruto system, perhaps fearing the change it brings.
In some 'working in a different world light novels', there are also characters that are native to the different world. They could be friends or allies of the main character, or they could initially be suspicious of this outsider who has entered their world. Their cultures and values would be different from the main character's original world, which would lead to interesting interactions.
Touya Mochizuki is the central figure. He's a likable protagonist who uses his wits and the functions of his smartphone to navigate the new world. There are also characters like Elze Silhoueska and Linze Silhoueska. They are sisters and become friends with Touya. They are skilled in magic and often accompany Touya on his adventures in the different world.
I don't know as I haven't read it. But usually in these types of novels, there is a main character who is the one that trips into the different world. There might also be some supporting characters in the new world like a wise old wizard or a friendly beast that helps the main character.
Since I don't know the details of this novel, I can't say for sure who the main characters are. But it's likely that there's the karate - practicing character who is the protagonist.
There could be a group of characters. One might be a creative type, like an artist or a writer, who is constantly inspired by the new and strange things in the different world. Another could be a bit of a loner, but they slowly open up as they experience the unique charm of the different world. And there could be a character who has a special ability that helps them navigate and understand the different world better, and together they form the main characters in this 'chillin different world life novel'.
I'm not sure specifically, but it could be the pharmacist who runs the different - world pharmacy. He or she would likely be the central character driving the story.