It's also possible that some non - human characters could be part of the harem. For example, some of the tailed beasts in human form (if that's possible in the context of the fanfiction). They would bring their own set of powers and a very different kind of relationship with Naruto compared to the human characters in the harem.
Sakura could also be included. She is a strong and independent character. Her medical skills would be useful in the harem, and her relationship with Naruto, which has evolved over time, could add an interesting dynamic to the group.
One interesting plotline could be the exploration of different relationships within the harem. For example, how Naruto interacts with each member in a unique way. Maybe he has to resolve conflicts between the harem members who might be jealous of each other.
One idea could be that Naruto, after achieving great power, somehow travels back in time and meets Kaguya before she turned evil. He then forms a harem with her and some other female characters from the Naruto universe who are also drawn to his unique power and kind heart.
In the fanfiction, Naruto could enter Kaguya's mind. He might discover her past traumas that led her to become so power - hungry and vengeful. By understanding her pain, Naruto could offer her forgiveness and a new path. He could show her a vision of a future where she is part of a united world, not feared or hated, but respected and loved if she changes her ways. This could be a powerful incentive for Kaguya to change.
Well, Naruto could change Kaguya in the fanfiction by introducing her to the concept of redemption. Given his own journey of facing his inner demons and coming out stronger, he might convince Kaguya that she can atone for her past sins. He may take her on a journey through the ninja world, showing her how people have rebuilt and thrived despite the chaos she once caused. This could make her re - evaluate her actions and change her perspective on the world and her place in it.
The Kaguya-sama manga is indeed finished. It ended after a successful run, leaving fans with memories of an engaging and enjoyable story. The final chapters tied up loose ends and delivered a conclusive ending.