Who might be the regular customers in Harry's shop in the fanfiction where he owns a shop?

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.

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.

Students from Hogwarts could be regulars. They might come during Hogsmeade visits. Also, young wizards and witches starting their careers in Diagon Alley would stop by. And of course, some of the older professors might pop in for a cup of their favorite brew.

Other potion shop owners might visit too. Not as customers in the traditional sense, but more to check out the competition. They might be curious about Harry's unique potions. And then there are the local wizards and witches in the area where the shop is located. They could need potions for daily life, like a potion to make their gardens grow better or a potion to keep their pets healthy.

His ninja friends like Sasuke, Sakura, and Kakashi would surely be regulars. Sasuke might come to buy things secretly to support Naruto's business. Sakura could be there to get supplies for her medical ninja work if it's a general store. And Kakashi would stop by for a chat and to pick up some new reading material if Naruto sold books.

Well, first of all, the genin teams would be regulars. They need to stock up on basic ninja equipment. Then, the older ninjas who are retired might visit to relive their younger days by buying things they used to use. And don't forget the wandering ninjas. If Naruto's shop becomes famous enough, they would stop by to buy rare items or get some rest and information at the same time.

Hermione would probably be a regular. She'd come to the cafe to study while enjoying a warm cup of Butterbeer latte. She might even bring some books from the Hogwarts library to read there.

I bet the regular customers would include some of Harry's old Hogwarts friends. Maybe Ron would stop by for a butterbeer and a chat. Hermione might come to relax after a long day of research. And of course, the Weasley twins would probably be there often, looking for new business ideas or just to have some fun.

Well, perhaps the plot could involve Harry using his magical knowledge to sell unique magical items in his shop. He might have a special section for potions, with rare ingredients sourced from all over the wizarding world. And he could use his fame from his adventures to draw in customers, like young witches and wizards who want to hear his stories while they browse through his wares.

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.