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.
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.
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.
Chapter 199, "You Found Out Long Ago?", is the clearest early answer because it turns Shang Shaojing's situation into a concrete plot event. The chapter turns that into something concrete by moving from Damn, the production team is actually being so generous this time,...
Chapter 647, "Let's Have a Sword Dance!", is the clearest early answer because it turns Pei Ye's situation into a concrete plot event.
Chapter 326, "Jiang Mingyu Stranded in a Foreign Land", is the clearest early answer because it turns Shen Lan's situation into a concrete plot event. Early on, And at this moment, on the other end of the Earth.. By the end, Ah, that's not right, in this place, your eyes should convey a....
Chapter 206, "Miss Su, Thank You So Much!", 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 Five minutes later, Xingxing led Ah Fu out of the room by the hand.
Chapter 293, "Hello Lei Ting, I am Chui'er Tuttu", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Damn, when will this hospital ever upgrade their beds?
Chapter 227, "There's Something Wrong with This Stepmother", is the clearest early answer because it turns Lonely Bird's situation into a concrete plot event. Early on, Your Four Pillars of Destiny is very strong, with wealth, authority,....
Chapter 349, "Everyone Who Went Out to Dinner that Night Got Poisoned!", is the clearest early answer because it turns Director Zhang's situation into a concrete plot event. The chapter turns that into something concrete by moving from The news quickly reached Ye Chu.
Chapter 390, "Is Jiang Li Commended by the Police Again?!", is the clearest early answer because it turns Shang Weiyang's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The bell rang for school to let out, and Tao Ying hurriedly grabbed...
Chapter 533, "Sister Li, When Did You Become a Clamp?!", is the clearest early answer because it turns Python Skin's situation into a concrete plot event. Early on, The sycophant had gone crazy too.. By the end, Although at the time he said it was a gift from the young master of....
Chapter 168, "Gu Family in the Capital", is the clearest early answer because it turns Capital's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Su Yinwan spoke those words with a pitiable expression, then lowered...