It could be Orochimaru. Since Orochimaru has a long - standing feud with Jiraiya and is always up to no good. If Naruto ditches Jiraiya, Orochimaru might see this as an opportunity to manipulate Naruto. He could try to convince Naruto that Jiraiya was holding him back and that he can offer Naruto more power, all while having his own evil plans for Naruto.
Well, in an anime mashup novel, one key element is the blend of different anime universes. For example, characters from a shonen anime might interact with those from a magical girl anime. Another element is the plot which often has to be carefully crafted to make these different elements fit together. And the art style, even in written form, might be influenced by the distinct visual styles of the animes being mashed up.
One novel approach could be using machine learning algorithms to analyze the context and requirements of the mashup project and recommend relevant APIs based on that.
One way to create an interesting anime mashup novel is by focusing on the emotions of the characters. Let's say you mash up an anime about loss and another about hope. You can explore how the characters from the 'loss' anime deal with the more positive environment of the 'hope' anime and vice versa. Also, use the visual aspects of the animes in your descriptions. If one anime has a distinct color palette, incorporate that into your writing when describing the new, mashed - up world.
There may be some interesting Kushina and Jiraiya fanfictions. You could search on platforms like Archive of Our Own or FanFiction.net. When looking, pay attention to the tags and summaries to find ones that focus on the elements you're interested in, such as their friendship or potential collaborations in the story.
One great fanfic could be about their adventures before Naruto was born. It might explore their relationship dynamics, how they trained together and supported each other. Maybe in this fanfic, Jiraiya tries to convince Tsunade to take on more dangerous missions with him, showing his trust in her abilities.