I don't have enough information to say exactly who Miu Sakamoto is in this context. They could be an author, a storyteller, or someone involved in creating this 'never ending story'.
I'm sorry, I don't actually know the specific 'Nicolae Miu story'. There could be many people named Nicolae Miu and without more context it's hard to tell a particular story.
One popular theme could be her training and growth as a fighter. Another might be her relationships with other characters in the story, like her comrades or mentors.
One common theme is the clash of their personalities. Miu is brash and outspoken while Kokichi is more devious. Their interactions based on these differences are often explored.
One popular 'Naruto and Miu' fanfiction could be about their adventures together in a new land. Maybe they discover a hidden jutsu that only they can master through their combined skills.
In the world of fandom, creativity is highly valued, but it should be within the bounds of propriety. Sexual fanfics are not in line with the values that most fan communities uphold. These communities are often made up of people of all ages and backgrounds, and such inappropriate content has no place in a healthy fan environment.
Since there's not much information given about 'miu sakamoto the never ending story', we can only make some general speculations. It could be a personal project of Miu Sakamoto. The 'never ending story' part makes me think of something that has an infinite quality. It might be a story that explores themes like time, eternity, or the cyclical nature of things. For example, it could be a story set in a magical world where time doesn't function in the same way as in our world, and events keep occurring in an unending loop, with characters constantly evolving and facing new challenges without a true end point.
One common theme is growth. Their relationship often serves as a means for both Shuichi and Miu to grow as characters. For example, Shuichi might become more confident in expressing himself, while Miu might learn to be more empathetic.
Well, aside from the big fanfiction platforms like Archive of Our Own and FanFiction.net, you could also check out some forums dedicated to the series that 'kenichi and miu' are from. Sometimes, fans will share their own fanfictions or recommend good ones in those forums. Another option is to do a general web search using specific keywords like 'kenichi and miu love fanfiction' along with the name of the series. This might lead you to some blogs or personal websites where fans have posted their works.