Maybe an adult Saiyan who has lost their way in the multiverse and ends up in the Naruto world. This Saiyan, with their battle - hardened exterior and powerful abilities, is initially shunned and neglected by the Naruto characters. However, as the story unfolds, they become the central figure as they try to use their skills to help the Naruto world while also dealing with their own past traumas.
It could be a young Saiyan who was sent to the Naruto universe as part of some sort of experiment by the Saiyan race. They are neglected because they seem so different from the ninjas. They would be the main character as they struggle to find their place and purpose in this new world.
Well, in a Naruto Neglected Saiyan Fanfiction, the story might revolve around a Saiyan who has amnesia and ends up in the Naruto world. Since they don't remember their true nature as a Saiyan, they try to fit in with the ninja lifestyle. However, because they unknowingly have Saiyan abilities that are very different from chakra - based powers, they are neglected by the ninja academies or teams. As the story progresses, they gradually start to discover their Saiyan heritage and have to decide whether to embrace it or continue trying to be a part of the Naruto world.
Maybe an outcast ninja. This person has always been on the fringes of the ninja society. Discovering the neglected sword gives them a chance to prove themselves. They could be someone with a lot of untapped potential who uses the sword to rise above the neglect they've faced.
It could be Samehada itself. Since the story is about it being neglected, it makes sense for it to be the main focus. It could have its own 'voice' and thoughts as it tries to deal with the situation.
It could be a new character created specifically for the fanfiction. Maybe a young ninja who discovers the neglected dragon and forms a bond with it.
It could be an orphan who has a natural talent for music but has been brought up in a ninja - dominated environment where music is seen as a useless skill. So, they are constantly neglected.
It could be an unknown Uchiha who was overlooked in the main story. Maybe they were born with the Rinnegan but due to some political unrest in their village, they were forced to hide their power and were thus neglected. In the fanfiction, they could come out of hiding and shock everyone with their Rinnegan - based abilities.
A young and talented Iwa ninja who feels left out could be the main character. He or she might be frustrated with how their village is always in the shadow compared to Konoha and wants to change that perception.
It could be an evil Saiyan who comes to the Naruto world to cause chaos. Maybe he's a rogue Saiyan who was exiled from his own planet and wants to take over Naruto's world.
The main antagonist could be the Sith Lord who oversees Naruto's neglect. This Sith Lord might be so blinded by the traditional Sith ways that he fails to see Naruto's potential, which in turn makes him the main obstacle for Naruto to overcome.
It could be a new villain created specifically for this fanfiction. Maybe a powerful ninja - like figure from another dimension who is jealous of Naruto's powers and wants to take them for himself while Naruto is in the Batman universe and feeling neglected, so he has to fight this new threat alone at first.