The antagonist could be a group of rogue ninjas. They don't believe in the power of the holy log or they want to use it for their own gain. They see Naruto as a nuisance and try to stop him from praying to the log. They might even try to destroy the log so that no one can have its power.
Well, it could be that Naruto is in a really tough situation. Maybe he's lost his chakra or his friends are in great danger. The holy log might be some sort of ancient and powerful object in this fanfic. He prays to it, hoping for some sort of power or guidance. It might also be that the log has a spirit or some connection to an old ninja legend that Naruto believes can help him turn the situation around.
Perhaps some of the more conservative and anti - Uzumaki elders in the village. They might still hold grudges against the Uzumaki clan and see Naruto as a potential threat. So they tie him to the log as a way to show their power and authority over him.
Perhaps Kaguya Otsutsuki is resurrected again, but this time with a stronger will and more dangerous plans. Since Naruto was the one who played a major role in defeating her before, she targets him first in this fanfiction.
It could be Sasuke. He has had his own dark journey and might turn against Naruto and Ino in this fanfiction. His newfound power and different ideals could make him see Naruto and Ino as threats to his goals.
In this case, Sakura could be seen as the antagonist, at least in that particular moment when Naruto tells her off. Since Naruto is the one doing the telling - off, it's because of something Sakura has done or said that has pushed him to that point.
Maybe a new, powerful and evil ninja from another land. This ninja could have come to the village and caused a lot of chaos, making Naruto believe that no one in his village was capable of protecting themselves or him. So he blames everyone for their weakness and starts to hate them all, with this new ninja being the root of the problem.
It could be a corrupt ninja from another village who wants to get rid of Naruto as he sees him as a threat to his own plans. This ninja could have framed Naruto to send him to prison.
Another possibility is that there is no single main antagonist. It could be a combination of misunderstandings, village politics, and personal issues within Kurenai herself that lead to her betraying Naruto. For instance, the village elders might be pressuring Kurenai to keep Naruto in check, and at the same time, Kurenai has her own doubts about Naruto's power which could be misconstrued as a reason to betray him.
It could be one of the harem members who has a hidden dark side. Maybe she's jealous of Naruto's closeness to others in the harem and decides to turn the rest against him, so she becomes the main antagonist.
It could be that there is no traditional antagonist. The conflict might be internal, with Naruto's own emotions towards Kushina being the main source of drama.