The old ninja masters could visit Naruto's shop too. They might be interested in seeing what new and innovative things Naruto is doing with his shop. Some of Naruto's former teachers like Kakashi could also drop by regularly. He might give Naruto some advice on running the business or just come to have a friendly chat while browsing the items in the shop.
His old friends from Hogwarts like Hermione and Ron could be regulars. They might come to support Harry's business and also to buy some useful things for their own magical lives. Maybe Neville would come to buy some special plants for his own gardening projects.
He might sell kunai. Kunai are basic and very popular weapons in the Naruto universe. They are small, easy to handle and can be used in various combat situations.
Ninjas would be the main customers. They need weapons for their missions, training, and self - defense. Whether they are from Konoha or other villages, they would come to Naruto's shop to get the best weapons.
Maybe some of the younger ninja like Boruto or Sarada could stumble upon Naruto's cave while on a training mission. They could be curious about this strange hermit - like figure in the cave and later realize it's Naruto. This could lead to a mentoring - like relationship between Naruto and the new generation.
In such a fanfiction, Naruto might sell ninja tools in his shop. He could use his own experiences as a ninja to recommend the best weapons or items for different missions.
Sasuke might be one of the main visitors. Their relationship has always been complex, and perhaps Sasuke is curious about Naruto's new venture. Shikamaru could also be a regular. He's smart and might be interested in the strategy involved in casino games. And then there's Kakashi. He seems like the type who would drop by now and then, just to keep an eye on Naruto and see how he's running things.
Sasuke could visit him. Despite their differences in the past, they have a deep bond. Sasuke might come to check on Naruto, or maybe he also wants some time away from the world and thinks Naruto's seclusion place is a good spot.
Perhaps it's a community building. Naruto is a very community - oriented person. He could own a building that serves as a place for the villagers to gather, like a community center. There could be a cafeteria, a place for kids to play, and rooms for meetings and celebrations.
His teammates, Sasuke and Sakura, would surely visit him. They are his closest comrades, and they would be worried about his condition.
His old mentor, Iruka, might visit. Iruka has always cared about Naruto. He could bring some supplies and words of encouragement. He might also be worried about Naruto's well - being and want to make sure he's okay living in the cave.