Well, from the Infinite Stratos series, Charlotte Dunois would be a great addition to the harem. Her kind and somewhat shy nature would contrast with Naruto's boldness. Laura Bodewig is also a possibility. Her strict military - like attitude would be an interesting dynamic with Naruto's more free - spirited ninja ways. And let's not forget Ichika's sister, Madoka Orimura. She could be in the harem, being drawn to Naruto's unique abilities and his caring personality.
Typically, you'll have the OC who is the center of the story. They might be a transfer student or someone with a hidden past. In the harem, there are usually the popular girls. Some could be the intelligent and studious type, always helping the OC with academic or strategic matters. Others might be the athletic ones, good at the mecha battles in the Infinite Stratos world. There could also be the mysterious girl who has her own secrets and draws the OC in with her enigma.
Potential female characters might include Hinata from Naruto. Hinata has always had a soft spot for Naruto and her gentle nature could be an interesting addition to the harem. In Mass Effect, Miranda Lawson could be in the harem. She is a genetically enhanced human with great combat and leadership skills. Also, Jack from Mass Effect could be part of it. Jack is a powerful biotic with a tough exterior but a complex personality. Each of these characters would interact differently with Naruto in the context of the fanfiction.
Hinata is a likely candidate. She has always had deep feelings for Naruto. On the island, her gentle and caring nature would make her an important part of the harem. Sakura could also be there. Despite her initial feelings for Sasuke, being stranded on an island with Naruto might make her see him in a new light.
Sakura could be one. She's a strong and intelligent character. Her interest in medicine might make her curious about the blacksmith's skills in creating precise tools. Hinata is also a possibility. Her gentle nature might be drawn to the blacksmith's hardworking and creative side.
In the Overlord world, Albedo could be one of the potential female characters. She is powerful and has a complex personality. In a harem fanfiction with Naruto, she might be intrigued by his different power system and his kind heart. Another could be Shalltear Bloodfallen. Her combat skills and beauty might make her interested in Naruto as well.
Definitely Hinata. Her love for Naruto is well - known, and in a post - apocalyptic world like Dead Rising, she would be by his side. Sakura could also join the harem. She has a complex relationship with Naruto and this new setting could change things. Then there's Temari. She's strong and independent, and in this new world, she might find herself drawn to Naruto. Karin, with her unique abilities, could also be part of the group of female characters in the harem.
One idea could be that Naruto, with his unique skills from the Naruto universe, somehow gets transported to the Infinite Stratos world. He might start by being confused by the technology but quickly adapts. He could form a harem as he befriends different female characters in the IS world through his kind heart and amazing combat abilities. For example, he might help a character in a difficult IS battle, and from there, a relationship starts to form.
Tenten could potentially be in the harem. She is a strong - willed and capable kunoichi. Her presence in the harem could add an element of action and adventure. Maybe she initially tries to fight against the evil Naruto but then gets drawn into his world and eventually becomes part of his harem.
Obviously, Naruto himself as the lycan. Hinata could be one of the harem members as she has a long - standing crush on Naruto. Sakura might also be part of it, adding some tension due to her previous relationship with Sasuke. Then there could be Ino, who is strong - willed and could have an interesting dynamic with Naruto in this context. And Tenten, with her skills, could also be a part of the harem.
Obviously Naruto would be the main character. For the harem, it could include Sakura. She is strong - willed and her medical skills could be interesting in relation to Naruto's ghoul nature. Hinata is also a likely candidate. Her gentle and loving nature could contrast with Naruto's more dangerous ghoul side. And then there's Tenten, who could bring her weapon - using skills into the mix.