The title indicates that Naruto is a central figure. However, in the Naruto world, many characters could be part of this fanfic. It could involve Naruto's family members in spirit, like his father Minato or mother Kushina. His peers from the Ninja Academy such as Shikamaru, Choji, and Ino might also play roles. And don't forget the Akatsuki members. If the story involves Naruto facing some threats during his 'neglected' state, Akatsuki could be the antagonists in this fanfic.
I'm not entirely sure as I haven't read this specific fanfic. But from the title, it might be about Naruto feeling neglected and then something related to his heart and perhaps his growth or a big event that changes things. It could be a story that delves into the emotional side of Naruto that is often overlooked in the original series.
The main character has to be Naruto. But we can't forget about the Hokage, like Tsunade. She could be involved in changing Naruto's situation. Maybe she gives Naruto a special mission or training that helps him break free from being neglected. Then there are Naruto's friends from Team 7. Sasuke's relationship with Naruto is complex, and in this fanfic, it could be explored in the context of Naruto's new standing. Sakura, too, could be part of the story, perhaps by finally seeing Naruto in a new light and helping him gain more acceptance in the village.
Obviously Naruto would be one of the main characters as it's about him being the neglected child. Other characters from the original Naruto series like Iruka, Sasuke, or Sakura could also be main characters, depending on how they interact with Naruto in this fanfic.
Besides Naruto, Yugito Nii could be a main character. She is a jinchuriki in Kumo, just like Naruto is in Konoha. They could bond over their shared experiences of being hosts. And there could be some of the Kumo elders who play important roles. They might be the ones who oppose Naruto's entry at first, fearing he could bring trouble, but then as they see how he can contribute to the village, their opinions change.
Gaara would probably be one of the main characters interacting with Naruto. They both have had difficult pasts and can understand each other on a deep level. Temari and Kankuro could also be important characters. Temari might spar with Naruto, while Kankuro could share his puppet - making skills with Naruto or learn from Naruto's combat techniques.
There could be members of the Gremory family. For example, Rias Gremory might be a key character. She could be one of those who initially neglect Naruto but later come to realize his potential. Another character could be Issei Hyodo, who might be in a position where he has to choose between the traditional Gremory way and Naruto's different approach.
I'm not sure specifically as it's a fanfiction and can vary greatly. But it could potentially have Naruto characters like Naruto himself or Sasuke, combined with some Tokyo Ghoul characters like Kaneki. Maybe there are also some original characters created for this fanfiction.
Obviously, Naruto is one of the main characters. Since it's related to him being involved with a neglected god. The neglected god itself is also a main character, as the whole story revolves around its relationship with Naruto. There might also be other characters like Sasuke or Sakura who could be involved in different ways. For example, Sasuke might be suspicious of Naruto's newfound connection with this god and it could cause some tension between them.
It could be that some of the neglected characters from Naruto, like Rock Lee for instance, are made main characters in this fanfiction and are paired with a Gremory character. Maybe a Gremory character who also has been somewhat overlooked in their own series. This would give a new perspective and new storylines to explore.
I don't know for sure as I haven't read this fanfic. But it's likely to have characters from the Naruto universe. Maybe Naruto himself could be one of the main characters, or perhaps some new characters created by the author related to this 'ashikabi' concept.