Nanashima could be the type to take risks in the relationship. He might be the one to initiate the first move, like asking Igarashi out on a date. Igarashi, though, would be the one to think things through carefully. He might worry about how their relationship would affect their school life and friendships, but eventually give in to his feelings for Nanashima.
As mentioned before, 'lemon' content is inappropriate, so I can't really discuss the characteristics in that regard. But in general 'kiss him not me' fanfiction, it often focuses on the romantic relationships between the characters, exploring different scenarios and emotions within the context of the anime's story and characters.
A 5x7 fanfiction for 'kiss him not me' might focus on a particular moment. For example, a 5x7 photo that holds a special memory for the characters. It could be a photo of a group outing, and in the fanfiction, the details of that day are explored, how the relationships between the characters developed based on that one moment captured in the 5x7 photo.
The ending of 'Kiss Him Not Me' manga ties up most of the storylines neatly. The main character finds love and resolution in a way that's satisfying for fans.
Common themes in 'kiss him not me yaoi fanfiction' include the characters' self - discovery. The male characters often discover their sexual orientation or their deeper feelings for another male character. There's also the theme of jealousy. When one character shows interest in another, it can lead to jealousy among other suitors or friends. And of course, the theme of love and attraction is central. The fanfictions tend to focus on how the characters are attracted to each other, both physically and emotionally, in a yaoi - based relationship.
In these crossovers, the theme of adaptation is quite common. The characters from 'kiss him not me' need to adapt to the rules, cultures, and character dynamics of the other world they cross into. Another common theme is the reimagining of character roles. For instance, a character who was a bit of a sidekick in 'kiss him not me' might become a hero in the crossover world. And of course, the theme of love and attraction still plays a role, but it's often tweaked and made more complex as new characters are introduced from the other franchise, leading to different love triangles or relationship dynamics.
Another trope is the 'hurt/comfort' one. For example, when the main character faces some sort of problem or gets hurt, one of the male characters comes to her rescue and comforts her. This allows for some really emotional and heart - warming scenes in the fanfiction.