Not sure. It depends on the specific context of the manga. Maybe Rika is a character or has some sort of connection, but without more details, it's hard to say exactly.
Their relationship in the fanfiction is likely to be full of mutual understanding. Since they are getting married, they must have a deep connection. Takato might be the more gentle and patient one, while Rika could be the strong - willed partner. They balance each other out.
Naruto could develop by learning to adapt his ninja skills to a more modern and zombie - filled setting. He might become more cautious as he realizes the different threats here compared to his ninja world. Rika could develop from being a normal schoolgirl to a more confident and brave fighter. She could learn from Naruto's fearless attitude and start using her own wits in more daring ways.