Obviously, Naruto is one of the main characters. He is the central figure from the Naruto universe. And then there would be characters from the orc army. There might be an orc chieftain who leads the orc army and interacts with Naruto, whether as an ally or an antagonist at times.
Most likely Naruto would be one of the main characters since it's in the Naruto universe and the title seems to imply a focus on a single character's story, which in this case is probably Naruto.
Since it's a fanfiction, the main characters could be any two characters from the Naruto series. It might be Naruto and Sasuke, as they are very popular characters and their relationship has a lot of potential for such a story. They could put aside their differences and form an army together.
Obviously Naruto himself would be a main character as the source of the clones. Maybe Sasuke could also be involved, either as an ally or an antagonist in relation to the clone army.
Most likely Naruto would be one of the main characters, since it's a Naruto - related fanfiction. There might also be his friends like Sasuke or Sakura who could be part of this army of glass concept.
Naruto is sure to be a central figure. Then there could be a new character, a half - demon who acts as a bridge between the ninja world and the demon army. Hinata might also be involved, perhaps using her Byakugan to discover secrets about the demon army. And of course, Kakashi could be there to guide Naruto and the others in dealing with this new threat.
Another storyline might involve Naruto trying to understand the orc culture within the fanfiction. He could learn their ways of combat, their social structure, and in turn, the orc army could learn from the ninja skills of Naruto. For example, Naruto teaching them how to use chakra in a different way.
Obviously, Naruto himself is often a main character. He might be the one taking on the role of the army general or be an important part of the army. Sasuke is also commonly seen. He could be a rival within the army or a key ally. And then there's Kakashi. His experience and wisdom could be crucial in guiding the army, whether he's directly under the general or acting as an advisor.
Naruto himself is often very popular. His never - give - up attitude and powerful jutsu make him a central figure in many fanfictions. Fans love to write about him leading the Naruto army into battle and coming up with creative strategies.
Sasuke could be one of the main characters. He might initially be skeptical about Naruto's plan to rebuild Revan's army but later come around and offer his skills. Another could be Kakashi. His experience and wisdom would be valuable in guiding the new recruits. Sakura too, with her medical skills, could play an important role in taking care of the army members during battles and training.
It could be a mad scientist - type ninja who creates the droid army. This ninja might be someone who was shunned by the ninja community for his unorthodox ideas about mixing technology and ninjutsu, and now wants revenge by using the droid army to take over.