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.
Perhaps the ramen shop is visited by a powerful and strange customer who claims to be from a far - off land. He has a unique request for the ramen that no one has ever made before. Naruto and the ramen chef must go on a quest to find the rare ingredients to fulfill this request. Along the way, they learn about the customer's culture and form an unexpected bond with him.
A plot could involve the ramen shop being in financial trouble. Naruto decides to hold a ramen - eating competition to attract more customers. People from all over the Naruto universe come to participate, and during the event, old rivalries are rekindled and new friendships are formed. In the end, the shop becomes more popular than ever.
Naruto and his son, Boruto, could be main characters. Boruto might not understand his father's love for the ramen shop at first, but as the story progresses, he comes to appreciate it. Another character could be Shikamaru. He might be there to relax and have some ramen while also using his intelligence to solve any problems that arise in the shop, like a sudden shortage of ingredients.
One possible plot could be that Naruto makes a huge mess at the ramen place while training or showing off some new jutsu, and as a result, he gets banned. Then he has to find a way to make it up to the owner.
One possible plot could be that Naruto discovers a new secret ingredient for his favorite ramen. This ingredient could be a rare herb only found in a hidden part of the forest. He then tries to convince Teuchi, the ramen shop owner, to use it in the ramen. Along the way, he has to face off against some ninjas who also want the herb for their own purposes.
One possible reason could be that he's had a bad experience with the taste. Maybe the ramen was made wrong one day and it left a really bad impression on him.
A plot could be that Naruto has to compete against a visiting ninja from another village who claims to be the best ramen eater. Naruto is initially intimidated but then realizes it's not just about eating fast but also enjoying the ramen. He starts to slow down and savor each bite, which actually helps him eat more in the long run. In the end, he wins and also makes a new friend from the other village.
Perhaps Naruto becomes a ramen chef to bring joy to the people of Konoha. He could start by working in Ichiraku Ramen and then decides to open his own shop. His friends support him, and he invents ramen that gives people different kinds of chakra boosts, which attracts all kinds of ninjas from different villages.
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.
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.
One interesting Naruto ramen fanfiction could be about Naruto opening a ramen chain across the ninja world. He uses his popularity and his love for ramen to bring people together over bowls of delicious ramen.
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.