Another plotline might be Naruto having to choose between different girls in the harem while also dealing with the challenges of exorcising powerful entities. He might face a situation where saving one girl means sacrificing his progress in exorcising a major demon, creating a moral dilemma.
Perhaps Naruto discovers that his chakra has a special connection to exorcising spirits. In the harem aspect, the girls could all have different powers that complement Naruto's. They could go on quests together, with Naruto as the leader, and along the way, their relationships develop in a romantic and comical way.
One possible plotline could be a dimensional rift that brings the characters of Naruto and Bleach together. Naruto characters end up in the Bleach universe or vice versa. The main character, say a Naruto character in the Bleach world, gradually forms relationships with multiple female characters from both universes, creating a harem. They could go on quests to close the rift while dealing with the different power systems and politics of the two worlds.
One possible plotline could be Naruto leaving Konoha due to feeling out of place because of the harem situation. Maybe he's overwhelmed by the attention of multiple characters interested in him romantically and decides to seek solitude or a new path outside the village.
One possible plotline could be that Hiccup, with his unique leadership skills and kind heart, attracts various female characters from his world. They might initially be drawn to his courage in facing dragons. For example, Astrid could be part of the harem, and together with other female Vikings, they form a group that supports Hiccup in his adventures and also have romantic interests in him. Another plotline could involve Hiccup meeting new female characters from different tribes during his travels, and they all fall for his innovative ideas about co - existing with dragons.
One possible plotline could be a situation where Naruto is split into two versions of himself, maybe by some sort of jutsu gone wrong. And as they get to know each other better, they end up kissing as a way to reunite or merge back into one. Another could be in a dream sequence where Naruto is exploring his self - worth and in this dream, he kisses his own reflection which then turns into another version of himself.
Well, a possible plotline might involve Naruto being possessed by the essence of the Shredder. As a result, he starts to act more like the Shredder in his own world. He could form his own group of followers similar to the Foot Clan and try to take over the ninja villages. His friends would then have to find a way to break the possession and bring back the old Naruto. Or, perhaps Naruto willingly takes on the Shredder role to gain new powers to fight a greater evil in his world, but he has to struggle with the darker aspects of the Shredder's personality.
One possible plotline could be that Naruto discovers he is a prince from a hidden or lost kingdom. This could lead to him having to learn royal etiquette while still trying to maintain his ninja ways. Another plotline might be that his status as a prince makes him a target, and he has to protect his new - found royalty while also protecting the Hidden Leaf Village.
One possible plotline could be Naruto having to adapt to his new - found disability. He might struggle with his self - worth as a ninja, since being crippled could limit his physical abilities. He could then focus on developing other skills, like his strategic thinking or his ability to train others.
Another plotline could involve the female characters in the harem having unique powers or abilities that they use to help Naruto in his battles. Maybe one of them has a special healing ability that comes in handy during a tough fight. And as they work together, their relationships deepen.
One interesting plotline could be the female Naruto having to deal with the different dynamics of a harem. For example, she might have to balance the affections of various male characters who are now vying for her attention in a new way. Maybe she uses her ninja skills in unexpected ways to handle the situation, like using her shadow clone jutsu to be in multiple places at once to manage all the relationships.
A frequent plotline is the training aspect. Naruto could teach some of Rias's peerage his ninja training techniques, which would be quite different from the normal training in the devil world. This can lead to new power - ups for the characters. There are also plotlines where Naruto is mistaken for a powerful devil or some other supernatural being in the 'High School DxD' world. This misunderstanding can create a lot of chaos and interesting story developments as he tries to clear his name while also dealing with Rias's harem and the various factions in that world.