There are fanfictions where Kushina's kiss is a sign of her forgiveness. Maybe Naruto made a big mistake in the story, and Kushina's kiss is her way of showing that she still loves him and believes in him. It could also be a part of a romantic sub - plot in a fanfiction. For instance, if the story has a bit of a twist where Naruto has feelings for his mother (not in a creepy way, but more in a spiritual connection sense), and the kiss is a moment of deep emotional connection between them.
One popular theme is exploring their relationship in an alternate universe. For example, a universe where Kushina didn't die and got to raise Naruto. It often delves into how their mother - son relationship would be different and how it would impact Naruto's growth and the Naruto - verse as a whole.
There might be a fanfic where Kushina is brought back to life briefly, and in that short time, she shares a kiss with Naruto as a way to convey all the love she had for him that was cut short when she died. It could also be a fanfic set in an alternate universe where the circumstances are different, and Kushina and Naruto have a closer bond than in the original story, leading to a kiss.
One popular kushina fanfiction might be those that explore her relationship with Minato before Naruto was born. It could focus on their courtship and how they overcame challenges together.
A common plotline in such fanfiction is the exploration of their relationship further. Since Kushina died when Naruto was young, fanfictions often show them getting to know each other better. It could be something like Naruto learning more about his mother's life before he was born, like her training as a ninja, her friends, and her dreams. And Kushina could get to know Naruto's friends and see how he has created a new family of sorts in the form of Team 7 and the rest of the village.
A common story in Kushina Uzumaki and Naruto fanfiction is time - travel. For example, Naruto might go back in time and meet his mother when she was young. They could then team up and face challenges together. This gives a chance to explore their relationship in a new and interesting way. Also, there are fictions where Kushina comes back to life during the Fourth Shinobi War and helps Naruto defeat the enemies.
I haven't come across a fanfiction with the exact title 'Naruto is Kushina's Sensei Kiss'. Fanfiction can cover a vast range of ideas and relationships, but this one seems rather unorthodox. It might not be a common theme. However, the Naruto fanfiction community is huge, so it's possible that someone has written something along those lines. Check different fanfiction platforms and use their search functions to be sure.
There are many 'kakashi and kushina' fanfiction stories out there. Some might focus on their friendship during their days in Konoha. For example, there could be stories where they train together and share their ninja experiences. Another type could be about how they team up to face a powerful enemy that threatens the village.
One popular story might be about Kushina's relationships in the harem, exploring how she interacts with different characters in a unique way. For example, it could show her forming strong bonds with her fellow harem members while facing various challenges together.
There are various 'Naruto Kushina' fanfictions. Some focus on their relationship as mother and son, exploring the unspoken bonds and how Kushina's spirit might have influenced Naruto even more than what was shown in the original series. For example, there could be fanfictions where Kushina gives Naruto advice through his memories during difficult times in his journey to become Hokage.
Well, it could be a really strange plot. Maybe it involves some sort of time - travel or alternate universe where Naruto has to take on the role of Kushina's sensei in a very different ninja world setting, and the kiss could be a symbol of some deep - seated connection or a way to transfer power. But this is all just speculation as I haven't actually read such a fanfiction.