Another possible plot is that the blacksmith, being an outsider in the Naruto world, has to deal with the cultural differences while building his harem. He might introduce new blacksmithing techniques that are not known in the Naruto world. The female characters in his harem could help him adapt to the ninja lifestyle, and in return, he could use his skills to upgrade their ninja tools. This creates a dynamic where they all grow together and face various challenges as a group.
Sakura could be one. She's a strong and intelligent character. Her interest in medicine might make her curious about the blacksmith's skills in creating precise tools. Hinata is also a possibility. Her gentle nature might be drawn to the blacksmith's hardworking and creative side.
In Naruto fanfiction, the combination of Fuinjutsu and blacksmithing can be really interesting. Fuinjutsu is all about sealing techniques, and when combined with blacksmithing, one can imagine creating weapons with sealed powers. For example, a sword that has a sealing jutsu inscribed on it to trap the opponent's chakra when it strikes. It adds a whole new layer of creativity to the Naruto universe.
In such fanfiction, the blacksmith could be a master of both metal and seals. They might create a chain with Fuinjutsu that can bind an opponent's chakra. This would be a great addition to a ninja's arsenal. They could also work on larger items like gates with Fuinjutsu seals to protect a village or a secret location.
I'm not entirely sure if there is a specific one with that exact premise. However, fanfiction authors are constantly coming up with new and unique concepts. Given the popularity of both Harry Potter and Naruto, it's possible that someone has written a story where Harry Potter is a blacksmith within the context of a Naruto fanfiction. It could be an interesting take on the characters and their worlds, perhaps exploring how Harry's skills as a blacksmith could interact with the ninja world of Naruto.
Sakura could be one of his apprentices. She has always been smart and determined, so she would be a great student. She could learn from Naruto how to use her chakra in the smithing process to create even better tools.
One possible plot could be that the Naruto world is facing a new threat that can only be defeated by unique weapons. Harry Potter, the blacksmith, arrives in the Naruto world. He starts to study the materials and techniques available in this new world. He combines his knowledge of magic - enhanced blacksmithing with the ninja's understanding of chakra. As he creates these new weapons, he also forms bonds with the Naruto characters. They train together to master the use of these new weapons, and ultimately they face the great threat together, with Harry's blacksmith - made weapons playing a crucial role in the victory.
In such a fanfiction, Naruto might use his new blacksmith skills to create unique weapons for the characters in the yaoi relationships. He could forge special items that symbolize the bond between the male characters. For example, he might make a pair of matching daggers for a couple, each with an engraving that represents their love for each other.
Sakura would be a likely candidate. She has a long - standing relationship with Naruto, so she could be part of the harem. Hinata is also a strong possibility as she has deep feelings for Naruto. And Ino, who has known Naruto for a long time and has her own charm, could also be in the harem.
Sakura could be in Naruto's harem. In the original series, she had a long - standing relationship with Naruto. In this fanfiction, with Naruto being 'dark godlike', she might be drawn to his new power and the mystery surrounding him. Also, Hinata would be a likely candidate. Her long - held feelings for Naruto could intensify with his new status, and she would be part of his harem due to her loyalty and love for him.