One plot idea could be Kazuma and Bishamon teaming up for a mission that no one else believes they can accomplish. They start off distrusting each other but as they face challenges, they gradually learn to rely on one another's strengths. Another could be a story where Kazuma discovers a long - hidden secret about Bishamon's past that changes their relationship dynamic.
A plot could involve Kazuma getting cursed and Bishamon is the only one who can break it. However, to do so, she has to sacrifice something dear to her. This creates a moral dilemma for her and also shows Kazuma how much she truly cares for him.
Their relationship can be developed through shared experiences. For example, they could go through a tough battle together. During the battle, Kazuma could protect Bishamon from a near - fatal blow, making her see him in a new light. And Kazuma could also admire Bishamon's strength even more.
One interesting crossover could be a story where Naruto's world is invaded by ayakashi from the Noragami universe. Naruto and his friends have to team up with Bishamon's shinki. They would learn about each other's powers and cultures. For example, Naruto's ninjutsu might be a mystery to the Noragami characters, while the concept of shinki could be new to Naruto.
One characteristic is the exploration of loyalty. Kazuma is extremely loyal to Bishamon, and this is often a central theme. For example, in many fanfics, Kazuma will go to great lengths to protect Bishamon no matter the cost.
Maybe a plot where Yato accidentally stumbles upon a secret of Bishamon's past that she has been trying to hide. This discovery could create a tense situation at first, but as Yato helps her deal with it, their relationship could grow stronger. For example, it could be related to a past trauma she experienced, and Yato's unique perspective on life and death could offer her new ways to cope.
Naruto has the power of the Nine - Tails, which is a huge source of chakra. Bishamon has her own reservoir of divine power. In a fanfiction, they could combine their powers by having Naruto transfer some of his chakra to Bishamon, who then uses it to supercharge her attacks. Or vice versa, Bishamon could bestow some of her divine essence on Naruto, allowing him to access new forms or abilities that are a blend of both ninja and divine powers.
A plot could also center around Megumin getting sick and Kazuma taking care of her. Since Megumin is usually so strong - willed and independent, seeing her vulnerable makes Kazuma realize how much he cares for her. He tries his best to get the right medicine and keep her comfortable, and in the process, their feelings for each other start to surface more clearly.
A more character - driven idea would be that Naruto and Yato meet and learn from each other's outlooks on life. Naruto, who has always fought for his friends and village, could teach Yato about the importance of having a strong community. Yato, who has a very different view of the afterlife and the divine, could show Naruto a whole new perspective on existence.
Maybe the OC is a hacker who is on a mission in OZ and Kazuma gets caught in the middle of it. They end up having to work together to solve the mystery behind a new threat in OZ. As they spend more time together, they start to develop feelings for each other. For example, while they are decrypting codes and fighting off digital enemies, they share personal stories and find common ground.
There's also 'The Unspoken Promise'. In this fanfic, the author delves into the unspoken connection between Kazuma and Bishamon. It's full of mystery and slow - burning romance. The descriptions of their interactions are really engaging and it makes you root for them as a couple.
A plot could be where Kazuma and Ayano are trapped in a magical realm together. They have to rely on each other to find a way out, and during this time, their feelings intensify. They might share a first kiss in this dangerous yet romantic setting.