One great 'Muichiro x Reader' fanfiction is 'A Meeting in the Mist'. It beautifully captures Muichiro's somewhat aloof nature while gradually developing a sweet relationship with the reader. The descriptive language used really makes you feel like you're in the Demon Slayer world with them.
One common theme is friendship development. Given their relationship in the original work, fanfics often explore how their friendship deepens and changes over time. It could be through facing various challenges together.
The relationship development between Muichiro and the reader has to be believable. It can't be too rushed. A slow - burn, where they gradually get to know each other, understand each other's quirks, and form a deep connection over time is much more appealing. Also, the setting should be in line with the Demon Slayer universe. Whether it's in the Demon Slayer Corps headquarters or on a mission, the details of the world should be well - described.
One great 'naruto kotetsu fanfic' is 'Kotetsu's Journey'. It really delves into Kotetsu's character, showing his growth from a relatively unknown shinobi to someone with a more significant role. It has a great plot that weaves in with the main Naruto storyline in an interesting way.
Adventure is also likely. Given Naruto's world full of missions and battles, fanfictions could involve the two characters going on an adventure together. They might face new enemies or explore uncharted areas in the Naruto universe.
Archive of Our Own (AO3) is also a great place. It has a well - organized tagging system, so you can easily search for 'naruto kotetsu fanfic' and find relevant stories.
Muichiro's death in the manga occurs during a particularly intense confrontation. His injuries accumulate, and he ultimately succumbs despite his valiant efforts.