Definitely Naruto has to be at the center. But aside from the obvious ones like Sakura and Hinata, characters like Anko Mitarashi can also be part of the story. She has a unique personality that can add a lot of spice to the harem jutsu - related plot. Also, Kurenai Yuhi could be involved. Her calm and composed nature contrasts with the chaos that the Harem Jutsu can bring. And don't forget about Karin, who has her own history with Naruto and could be an interesting addition to the harem in fanfiction.
Naruto himself is often involved. Since he's the main character, fanfiction writers like to explore how he would use or be affected by the mind transfer jutsu. Sasuke is another common one. His complex personality and powerful abilities make for interesting scenarios when combined with the mind transfer jutsu. Kakashi too, as he is a very intelligent and experienced ninja. Writers might explore how he would use the jutsu for strategic purposes.
Naruto is often involved. Since he is the main character of the original series, it's natural that in fanfiction about Forbidden Jutsu, he would be curious or accidentally get involved with these powerful techniques. Sasuke is another common character. His thirst for power could lead him to seek out Forbidden Jutsus.
In addition to Sakura and Hinata, characters like Ino might be included. Ino is Naruto's friend and has her own charm. Also, Tenten could be part of it. She is a strong - willed character and could add an interesting dynamic to the harem. And sometimes even female characters from other villages might be added to the harem in fanfiction, like Temari. This broadens the scope of the relationships and interactions in the fan - created story.
Obviously Naruto is one of the main characters. And then there are usually some of the female characters from the Naruto series like Sakura, Hinata, and maybe even some of the female ninja from other villages. They are often part of the harem that revolves around Naruto.
Gaara could also be part of the fanfic. Since he has his own unique abilities related to sand, there could be an interesting interaction between his powers and Naruto's summoned creatures. For example, Naruto could summon a water - based creature and they could team up with Gaara to fight an enemy that is strong against both sand and water.
Luna Loud is also a popular character in such fanfictions. Her cool and unique personality might attract multiple characters towards her, leading to a harem - like plot. Her love for music could be a factor that draws other music - loving characters to her in the fanfiction.
Naruto himself is often a main character in such fanfiction as he is the protagonist of the original series and has a knack for learning new jutsus.
Naruto himself is often a main character in these fanfictions as he has a connection to the Hiraishin no Jutsu through Minato. Also, Minato is frequently featured as he was the original user of the jutsu. Sasuke can also be involved as he and Naruto have a complex relationship and their interactions can be explored in relation to the jutsu.
Naruto himself is likely to be involved. After all, he's always at the center of new jutsu developments in fanfiction.
For Ichigo's harem, Orihime and Rukia are very common. Orihime with her kind heart and strong powers of healing, and Rukia being the one who introduced Ichigo to the world of Soul Reapers. In Naruto's case, Hinata and Sakura are often part of his harem. Hinata because of her long - standing love for Naruto, and Sakura being one of Naruto's closest friends.