To start writing your karmagisa fanfiction, begin by imagining a unique situation for them. For example, you could place them in a different country for a study exchange. Next, focus on their dialogue. Since Karma is a bit mischievous and Nagisa is more gentle, their conversations should reflect these traits. Also, don't be afraid to add some conflict, like a misunderstanding between them. This will make the story more engaging. You can also look at other fanfictions for inspiration, but make sure to put your own spin on it.
First, you should really understand the characters of Karma and Nagisa. Watch the original show carefully to get their personalities right. Then, think of an interesting scenario or plot. It could be something like a school project they have to do together. Start with a simple outline, like how the story will begin, what the middle part will be about, and how it will end.
Well, the first step in writing a karmagisa fanfiction is to study the source material thoroughly. Know their backstories, their dreams, and their fears. Once you have a good grasp of this, come up with a concept. It could be a time - travel story where they go back to their childhood days. As you write, build their relationship gradually. Show their interactions, both positive and negative. For instance, Karma might tease Nagisa, but Nagisa could respond in a cute way. And don't forget to proofread your work to avoid grammar and spelling mistakes.