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.
One great fanfiction could be where Mutsumi and Shinomiya go on a trip together. They might start off as friends but gradually realize their deeper feelings. It could include sweet moments like sharing an umbrella in the rain and stealing glances at each other.
It's about a girl who loses a lot of weight and suddenly finds herself surrounded by four popular boys at school. The story follows her newfound popularity and the romantic interests that develop among them.