I would recommend 'Douma's Secret Admirer'. In this fanfiction, the reader is a shy character who secretly admires Douma from afar. It's full of cute and endearing moments as the reader tries to get closer to Douma without being too obvious. It's a really heart - warming read.
Well, the plot could involve Naruto being reincarnated as Douma. He would have to deal with Douma's memories and powers. Naruto, having his own moral code, might struggle with the darker aspects of Douma's character. He could use his ninja skills to fight against the enemies that Douma had in his world, but in a more heroic way than Douma did. Maybe he'd form new alliances with the characters in Douma's world and bring a new perspective to the power dynamics there.
In a 'kokushibo meets tanjiro fanfiction', one possibility is that Kokushibo senses something different about Tanjiro right away. Maybe it's the fact that Tanjiro has a unique scent or an energy that Kokushibo has never encountered before. Tanjiro, being Tanjiro, would be ready to face Kokushibo head - on, but also be open to communication if there's a chance. The story could explore their different views on the world of demons and slayers, and how they might come to understand each other better through their encounter.
Common themes in douma x kotoha fanfic can include redemption. Maybe Douma has some past actions that he needs to make up for, and Kotoha plays a role in that process. Also, there is often a theme of self - discovery. As they interact more, they learn more about themselves through the eyes of the other. This can be a very interesting aspect to explore in these fanfics as it adds depth to both characters.
Fanfiction.net is also a classic site for finding 'Douma x Reader Fanfiction'. It has been around for a long time and has a vast amount of content. However, the search function might not be as advanced as AO3, but with a bit of patience and browsing, you can still find some excellent stories.
For Tanjiro, he could become more understanding of the complex nature of demons. Meeting Kokushibo, a powerful and complex demon, might make him realize that not all demons are simply evil. Kokushibo, on the other hand, could start to have some doubts about his loyalty to Muzan. Tanjiro's tenacity and belief in the good of all might start to chip away at Kokushibo's cold - hearted exterior.
The battle of Yoriichi vs Kokushibo can be found in the advanced stages of the Demon Slayer manga. It's an intense and highly anticipated confrontation. The build-up and action are both masterfully depicted.
Well, one place to start looking for douma x kotoha fanfic could be fanfiction.net. There are often a variety of works there. Another option is Archive of Our Own (AO3). Some fanfics might focus on their unique relationship, perhaps exploring how they interact in different settings or how their personalities mesh together.
Naruto's normally bright and positive personality might become more conflicted. Since Douma has a more complex and often morally ambiguous nature, Naruto would have to grapple with new emotions. He might become more reserved as he tries to figure out how to handle Douma's powers without losing his own identity.
I can't help you. If you have any other questions or needs, please let me know. I'll do my best to answer them.
While waiting for the TV series, he could also click on the link below to read the classic original work of " The Legend of Mortal Cultivation "!