Well, Kami is the prime candidate for the main antagonist as per the title. But it's possible that in the fanfiction, the author might introduce some sort of corrupted version of Kami or a false Kami who is the real source of the betrayal. This could add an interesting twist to the story, but still, Kami or something related to Kami is expected to be the main antagonist.
Obviously, Kami would be the main antagonist. Since the title says 'naruto betrayed by kami', Kami is the one doing the betraying, which makes him the bad guy in this fanfiction.
It could be Kami, but there might also be other forces at work. Maybe Kami is being influenced by some other dark entity. So while Kami is the one directly betraying Naruto, there could be a deeper, more hidden antagonist pulling the strings. However, based on just the title, Kami is the most likely main antagonist.
Chapter 219, "Five Thousand Jin??!!", is the clearest early answer because it turns Director Sun's situation into a concrete plot event. The chapter turns that into something concrete by moving from Qi Tianyu was somewhat freaking out.
Chapter 137, "Lai Fu's Death Has Another Cause", is the clearest early answer because the violence around Yintang becomes final instead of hypothetical. The chapter turns that into something concrete by moving from Jiang Li personally went to Lai Fu's tomb and performed a small...
Chapter 226, "Live Fortune Telling!", is the clearest early answer because it turns Zhao Lang's situation into a concrete plot event. The setup is What was all that before then?, but the pressure keeps building through Jiang Li quickly tapped the screen twice, and a red packet link that....
Chapter 245, "More Than Meets Your Match!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Jiang Yan became even more smug upon hearing this.
Chapter 16, "He Actually Fell Asleep", is the clearest early answer because it turns Jiang Shixu's situation into a concrete plot event. It opens with Just as the words fell, Jiang Shixu swiftly cast his eyes downward.
Chapter 178, "The Group's Favorite Belongs to No One but Her!", is the clearest early answer because it turns Wen Jiaojiao's situation into a concrete plot event. Early on, Wen Jiaojiao is just too unreasonable, why does she have to single....
Chapter 156, "Group Morning Run!", is the clearest early answer because it turns Shu Yan's situation into a concrete plot event. Early on, Flash Change, who was always tardy, was late again today.. By the end, Soon after, the meditative He Yun also walked over..
Chapter 27, "Signing Jiang Yan is fine, but you have to follow along too.", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. Early on, They had spent an entire year gradually inviting a few people..
Chapter 11, "She Smiled, He Panicked", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter gives readers a real answer by opening on After a meeting, Shang Shaojing pinched the bridge of his nose,...
Chapter 66, "This Sister Really Can Hustle!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event.