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.
Maki in fanfiction usually has a fierce loyalty to her friends, especially Yuta. She is the type to fight for what she believes in. Yuta is sometimes portrayed as being a bit naive in the ways of the world outside his own small circle, but his pure heart makes him endearing. In many stories, their different personalities create an interesting dynamic, like in a story where Maki's boldness gets them into a risky situation and Yuta's calm thinking gets them 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.