Sakura could also be a main character. She's a strong ninja in her own right. In a fanfiction like this, she could be involved in treating the injured when the Hellsing - related chaos starts. Maybe she also tries to understand the unique physiology of Alucard. And Integra from Hellsing. As the head of the Hellsing organization, she could be the one trying to establish some sort of order between the two worlds.
One possible plot is that there is a breach between the Naruto universe and the Hellsing universe. This causes chaos as demons from Hellsing start to invade Konoha. Naruto, being the hero, tries to figure out how to stop them. Alucard arrives, not entirely as an ally at first. But as they both realize the common threat, they join forces. Naruto learns about the different nature of the enemies from Alucard and adapts his ninja skills accordingly.
Aside from Naruto and his immediate family, characters like Kakashi could also be important in this fanfiction. He was Naruto's mentor, and he would surely be there to welcome them back. And Sasuke might also play a role, as he is Naruto's friend and has a connection to the village too.
Obviously, Naruto is likely to be one of the main characters. Since it's 'naruto gamer of konoha', he's probably at the center of the story.
Obviously Naruto is one of the main characters as it's related to him. And the Nine - Tailed Fox would also be a central figure considering the title. Also, characters like Sasuke and Sakura are likely to be important as they are Naruto's friends and comrades in the original Naruto series and would surely be involved in the events of the fanfiction.
Most likely Naruto would be one of the main characters. Since it's a Naruto - centered fanfiction, he would be at the heart of the story. There might also be other characters like Sakura, Sasuke, or Kakashi who could be involved in the plot related to the ghosts in Konoha.
Sakura could be one of the main characters. She might be part of the harem and her reaction to Naruto leaving could be a significant part of the story. Maybe she tries to bring him back or has her own journey of growth while he's away.
It could be Orochimaru. He has always had an interest in Konoha and its secrets. Maybe he decides to launch a full - scale invasion this time to get his hands on something he desires.
It could be a corrupt elder in Konoha. They might be power - hungry and see Naruto as a threat to their control. So they manipulate the situation to make Naruto the enemy.
Maybe Danzo could be a major antagonist. He's always been a shadowy figure with his own agendas. He might see Naruto as a threat to his secret operations and influence in Konoha, and thus play a key role in getting Naruto executed.
Obviously Naruto has to be one of the main characters. He'd be the energetic and sometimes clumsy student who is always getting into trouble but has a heart of gold. Sakura would also be a main character, the smart and strong - willed girl who is often exasperated with Naruto's antics. And Sasuke, the cool and aloof student who has a mysterious past and is the object of many students' admiration.