13 Years Before the Opening of the Bridge...At the bottom of the ocean, a figure finishes draining the heat and radiation from an underwater volcano. He will need to move away for the first time in eons in order to feed again. Then he senses sources of radiation on the surface, moving. Shocked, he muses that ever since the Cataclysm many millennia ago, there should be no other living users. He decides to investigate and starts swimming to the surface.
Nick Tatopoulos and his crew sail the Heatseeker monitoring Kaiju activity. With all the recent battles his adopted son Zilla Jr. and the other Defenders have been fighting, Nick is filled with regret and wishes the new Kaiju would be sentient and able to be reasoned with more often so that conflicts don't end in bloodshed. He dislikes the mentality of putting human lives above Kaiju lives. His crewmates detect a massive Kaiju approaching with the sonar.
Nick uses a device to communicate with Zilla, warning him about the possible incoming threat. He warns that the approaching creature is much larger than him and weighs about 90,000 tons. Nervous, Zilla notes that they are a few hours away from Monster Island, so they should head there.
As the hours pass, Nick and his crew discuss the Kaiju. According to the sonar, its body is symmetrical and proportioned, so it is not a mutated animal like the ones they normally face, but a natural creature. It is similar in size to Grand King Ghidorah and they can detect massive levels of radiation coming from it.
Zilla arrives at the beach and takes a moment to catch his breath. Godzilla Junior appears and asks what he wants, so Zilla explains the situation. Godzilla complains about Zilla dragging him into this mess by luring it to his home, but he supposes there's no choice but to confront it now.
As it approaches the island, the Alpha Predator senses Godzilla and Zilla and wonders why Godzilla is not trying to eat the smaller Zilla. No matter, it is time to defend his title and his world.
The Alpha Predator makes landfall, causing a tsunami in his wake. Zilla runs away and avoids it, but Godzilla just braces himself against the water until it passes, Godzilla complaining about him showing off. The Alpha Predator stands up and the pair are left gawking. He looks very similar to a member of Godzilla's species, but he's a head taller and a lot wider, all muscle. He's just as surprised to see them as they are to see him. He muses that he was sure he was the last of his kind; this was the judgment of the Great One: to wipe out all but him for the sake of the world. He speaks his first spoken words in eons, "What are thou?"
Godzilla, hoping this can end peacefully, introduces himself and asks what he wants. The Alpha Predator, speaking in Flowery Elizabethan English and using the Royal "We", asks if Godzilla is a predator and where he came from. Confused, Godzilla says that yes, he can eat meat, and he was born from an abandoned egg and raised by humans. Upset, the Alpha Predator says that is not possible; he was the only surviving member of his kind. For there to be more, the humans must have genetically engineered them, and such an action cannot be tolerated for they are threats to the world. He asks if Godzilla is a threat, and he says he is not. He is protector of this island and its inhabitants.
The Alpha Predator says defend them if he can and attacks. He and Godzilla grapple, but he is much stronger and forces Godzilla to the ground. Zilla tackles him away, but groans in pain and says it felt like hitting a mountain. The Alpha Predator taunts Godzilla for not fighting his own battles, but he retorts that there's no such thing as fair or unfair in battle. They fight again, and their foe easily shrugs off Godzilla's claws and Nuclear Pulses and Zilla biting his tail.
The Alpha gets several hits in on Godzilla, but sees the injuries heal up. The Alpha backs away. Godzilla goes for his Atomic Breath, but is shocked when the Alpha fires one of his own. The blasts collide, but Godzilla's overpowers the Alpha's, forcing him to duck.
Godzilla gives him a chance to end this and leave. If he will not, he may be forced to kill him to defend those under his protection. The Alpha thinks he is strange for not behaving like a regular predator. He's impressed to realize Godzilla isn't even tired from using his Atomic Breath, while he is. He asks Godzilla how much he values his allies. Lightning fast, he turns around, grabs Zilla who had been sneaking up on him, slams him into the ground, and pins him with a foot. He charges up his Atomic Breath. Desperate, Zilla retaliates with his napalm breath, but it doesn't even bother him.
Right before he fires, Godzilla dives in and shields Zilla with his body. He screams in pain, but endures it and knocks the Alpha away with a Nuclear Pulse punch.
The Alpha gets up and says he is pleased and Godzilla passed his test. Incredulous, they ask what he is talking about, and he explains that Godzilla's power and compassion for others have proven he is worthy to defend the planet. He gladly passes his title of Alpha Predator to him. Godzilla asks what that means, and he says it is the duty of the Alpha Predator to keep nature in balance and all the other predators in check. Godzilla snorts and says he had already been doing that. As long as the stranger doesn't try to harm innocent humans or his friends, he has no quarrel with him. The stranger agrees and turns to leave, saying he wants to find radiation to feed on and company that won't speak so strangely. Zilla angrily says he's the one speaking strangely, then the two ask him his name.
The stranger says he has no true name, but eons ago, the ancient humans nicknamed him Gojira. He swims away. Zilla comments on the coincidence, since Gojira is another way to say Godzilla, then speculates that Gojira was Godzilla's distant ancestor. Godzilla says if that is true, it doesn't matter. The only family that matters to him are his mother Azusa Gojo and his father Godzilla Senior. Zilla then worriedly speculates that Gojira would have probably eaten them if they had lost the fight. Godzilla teases him by saying Zilla would be safe because he smells and tastes like fish.
As Gojira swims, he feels the planet is in good hands with Godzilla and his friends, and hopes that when the time comes, they will be able to stand up to his former friend the Great One, apparently referring to Bagan. He senses great radiation coming from the Hawaiian Islands and heads in that direction.