Maybe she kisses one of her rivals in a competition. This could be a way to throw the rival off - guard or perhaps it's a moment of sudden understanding between them that leads to the kiss. For instance, if they are in a magical competition and Sakura realizes that the rival has a side to them that she never noticed before, and in a moment of impulse, she kisses them.
Sakura could kiss a character who is usually in the background. It could be someone who has always secretly admired her, and in a particular situation, like a festival or a moment of celebration, Sakura, caught up in the moment, kisses this character, which then sets off a whole new chain of events in the story.
Well, it could be a new character introduced in the fanfic. Maybe a mysterious stranger who has some special charm that attracts Sakura.
Another possibility is a civilian she has known for a long time in Konoha. Perhaps someone who has always admired her from afar, a merchant who supplies the hospital where she works. He might have shown his love and support for her over the years, and finally, Sakura realizes her feelings for him and decides to marry him.
It could be a jealous rival. Maybe there's another ninja who has feelings for Sakura and is trying to keep her away from Sasuke. So Sasuke has to catch her to prevent this rival from taking her away.
One possible plot could be that Sakura is in an alternate universe where she has lost her memory and kisses someone else thinking they are her true love. Another could be that she is under a spell which makes her kiss someone else, and then she has to deal with the consequences of that action.
Well, it could be a story where Sasuke saves Sakura from someone else who might be a threat. Maybe it's an enemy from another village or a rogue ninja. Sasuke, with his powerful skills, steps in to protect Sakura.
It could be a story about two characters from different worlds finally coming together. Maybe Kakasji has been secretly in love with Sakura and after a series of adventures and misunderstandings, they share a kiss that changes their relationship forever.
One possible plot twist could be that the person Sakura is marrying is actually under a spell. For example, an enemy might have cast a love spell on him to get close to Sakura for some devious plan. Another could be that Sakura discovers at the last minute that the man she's about to marry has a hidden identity. Maybe he's a long - lost relative of an enemy she thought she had defeated. It would add a lot of drama to the story.
Maybe it could be her long - time rival. This would be really unexpected because they've always been at odds. But perhaps there was some hidden admiration or understanding between them all along that they didn't realize until later. It would completely change the dynamic of their relationship from enmity to love, which would be a very interesting turn of events in the fanfic.
A Sasuke and Sakura fanfic where they kiss can be really interesting. It might explore their complex relationship. In many 'Naruto' storylines, their relationship is full of tension and unspoken feelings. A good fanfic would build on that, perhaps showing Sasuke finally expressing his deeper emotions through that kiss. It could also show Sakura's reaction, whether it's surprise, joy, or a mix of both.
I'm not entirely sure if there is a specific 'Kakasji Kisses Sakura' fanfic. However, the world of fanfiction is vast. It could be that some independent writer has created one. You could also try reaching out to fan communities dedicated to the relevant fandoms and ask if anyone has come across such a fanfic.