One idea could be that the shop owner has a secret past as a powerful ninja who retired due to an injury. He now uses his knowledge of ninja tools and techniques to run a shop that attracts all kinds of customers. For example, he might have a special section in his shop for rare and ancient ninja weapons that are sought after by collectors and current ninjas alike.
The shop owner could be a non - combatant with a unique ability to sense the chakra in ninja tools. This allows him to always have the best inventory in town. He has a friendly rivalry with other shop owners in the area. One day, a group of rogue ninjas target his shop to steal a powerful artifact he has just acquired. He has to team up with some of his regular customers, who are ninjas, to defend his shop and the precious item.
The plot might involve the candy shop owner competing in a local fair or competition to prove that their candies are the best. They might face challenges from other shops or even some ninja who think they can make better 'ninja - candies'. Along the way, they make new friends among the villagers, and also attract the attention of some important ninja who see potential in their unique candies for use in missions.
It could be an old veteran ninja who, after years of service, decided to open a shop. He has a gruff exterior but a heart of gold. He uses his war stories to attract customers, especially the young ninja trainees who are eager to hear tales from the front lines while they browse his selection of kunai and shuriken.
One possible plot could be that a new and mysterious ingredient is discovered in the Naruto world. This ingredient is added to the ramen in the shop, and it gives those who eat it special powers. Naruto and his friends then have to protect the ingredient from villains who want to use it for evil.
There are fanfictions where the shop owner is an outsider to the main Naruto world but has a special ability to sense the chakra of the items in his shop. He uses this to find and sell only the best quality ninja equipment. One day, Naruto himself comes to the shop looking for a special weapon. The shop owner, recognizing Naruto's potential, gives him a discounted price on a powerful kunai that has a special history and was once used by a great ninja. This kunai then plays an important role in Naruto's next big battle.
Naruto would definitely be one of the main customers. He has a well - known love for candies. His friends like Sasuke and Sakura might also stop by sometimes. Then there are the younger ninja trainees who are always looking for a sweet treat after a hard day of training.
In fanfiction, a Naruto shop owner can be unique because of the items they sell. They might have access to rare and ancient ninja artifacts that no one else has. For instance, a shop owner could sell a sword that was used by one of the Legendary Sannin. This would attract all kinds of customers, from powerful ninjas to collectors.
In a 'naruto runs a shop' fanfiction, he could run a pet shop. Naruto has always had a connection with animals. He rescues and rehabilitates injured animals and then finds them new homes through his shop. He might also have some special ninja - animal hybrids in his shop that are a big draw for customers.
Well, Naruto might sell ramen in his shop. After all, he loves ramen so much. He could have his friends like Sasuke and Sakura helping out sometimes. Maybe there would be special ninja - themed items for sale too.
A possible interesting plot could be Naruto discovers a hidden ninja village where parkour is the key to unlocking ancient secrets. He has to master new parkour skills to traverse the village's dangerous terrains filled with traps and challenges, all while facing off against a rival ninja group who also wants the secrets.
One possible plot could be Naruto being summoned into the DxD world by some sort of magic accident. He might initially be confused but quickly adapt his ninja skills to the new environment. He could team up with some of the DxD characters to face a common enemy, like a powerful fallen angel or a rogue devil. His Rasengan and shadow clone techniques would be quite unique in this world.