One idea could be that Naruto, while on a mission in an unknown land, meets Guren and gradually other characters are attracted to him, forming an unexpected harem. Maybe Naruto's unique ninja skills and his kind heart draw them in.
A possible plot is that Guren is initially Naruto's enemy but as they interact more, she starts to fall for him. And then other female characters from different clans see Naruto's charm and his way of changing Guren, and they also join the harem. For example, they might all team up to fight a common, greater enemy together which deepens their relationships.
Perhaps Naruto gets lost in a mysterious forest and stumbles upon Guren. As he tries to find his way out, his positive attitude and determination make Guren like him. Then, through some events like a village festival or a joint training session, other female characters start to have feelings for Naruto, creating the harem.
Hinata could be a potential member. She has always had a crush on Naruto. Her gentle and shy nature would add an interesting dynamic to the harem, especially when contrasted with Guren's more assertive personality.
One idea could be Naruto somehow finds himself in a situation where he has to team up with Tayuya frequently. As they interact more, a harem starts to form around Naruto, with Tayuya being one of the key members. The plot could involve them going on missions together and Naruto gradually realizing his feelings for Tayuya among the others in the harem.
One idea could be that Naruto accidentally enters a different dimension where he meets Fuu and gradually attracts other characters who form a harem around him. They could go on adventures together, fighting against new threats in that dimension while Naruto tries to find his way back home.
Maybe an evil villain casts a spell on Naruto that draws a harem of female ninjas to him, thinking it will distract him. But Naruto uses this new situation to his advantage. He has the girls help him train in new ways and they all form a unique bond as they work together to face the real threats to the village.
A more complex plot could be that there is a powerful enemy that threatens both Naruto's world and the world of Rias. Naruto and Rias's harem have to team up to defeat this enemy. Along the way, they face many challenges that test their abilities and relationships. Naruto's positive attitude and never - give - up spirit start to influence the members of the harem, and they in turn show Naruto new ways of using magic and power.
One idea could be that Naruto discovers a hidden realm full of monster girls. They are initially wary of him but as he shows his kind heart and powerful ninja skills, they start to fall for him. For example, a fox - like monster girl might be drawn to his own connection with the nine - tailed fox.
A possible plot could involve a competition among the members of Naruto's harem. Since they are all in love with Naruto in this genderbend scenario, they might compete in ninja tasks or challenges to prove their worth to Naruto. Maybe there could be a tournament where they show off their jutsu, and Naruto has to judge not only their skills but also how their actions affect their relationships with him.
One idea could be that Naruto discovers Tayuya has a group of friends who are also interested in him, creating a harem situation. He has to navigate his feelings for Tayuya while also dealing with the others. Maybe they all go on missions together and Naruto gradually realizes his deeper connection with each of them.
Another plot could be that Naruto is mistaken for an Avatar in the Avatar world. As he tries to clear up the misunderstanding, he gets involved in local politics and relationships. The female characters see his honesty and kindness, and gradually, a harem - like situation develops around him.
One idea could be that Naruto, through some magical or mysterious event, ends up in a different universe where he has to deal with a harem of various characters from different anime. For example, he might find himself in a world with characters from Fairy Tail, One Piece, and Bleach all vying for his attention. Another could be that Naruto's already large group of friends in the Naruto universe start to develop romantic feelings for him all at once, creating a sort of accidental harem situation. Maybe Sakura realizes she always loved Naruto more than Sasuke, Ino also has a change of heart, and then some new female characters are introduced who also fall for him.