The latest Crunchyroll original series Onyx Equinox recounts the story of a mythical ancient Mexico where devotees are caught in the middle of the battle between the gods. However, young Izel has to suffer the most as he has to make the final sacrifice. He understands the brutal battle of the gods and consequently becomes a pawn in it, maybe hoping that he could make things better. The first episode of the show opens in a crowded city. Zyanya, a young woman who is training, can get the upper hand on her partner, but right at that moment, the sky suddenly goes red. After a warning horn, the messenger lets everyone know that a sacrifice failed and trouble will soon follow.
Zyanya realizes that her parents might need her help, but just as she gets there in time, she sees her mother swallowed by emerald slime that rises from the ground. These slimes rise all over the city and consume people to become monsters. However, they can be defeated with an obsidian obelisk that burns the beasts when they touch them. Unfortunately, it is not big enough to protect everyone, and Zyanya tries to lead as many as she can people to the obelisk’s grounds.
A priest commits suicide by slitting his throat in an attempt to please the gods. Although his blood rises from his dead body and summons gods Xoo and Cocijo, it’s too late. The creatures in the city kill all the people they have held captive. The blood of the people is absorbed and summons Mictlantecuhtli, the god of the dead. He rips Xoo in half while Cocijo flees. He then demolishes the city as Zyanya stands helplessly outside the blast zone, and the whole town is obliterated in front of her.
While the survivors are running to find cover, god Quetzalcoatl possesses a child and meets other gods in a hut. They talk about Mictlantecuhtli and the destruction of the city. They conclude that his actions are certainly an act of war since he is taking away sacrifices from other gods. They decide to close the gates of the underworld, which will leave the human world just for them so that they will have more sacrifices. Quetzalcoatl chooses to take it upon himself to do the task, but Tezcatlipoca lets him know that he will begin humanity’s destruction at the equinox.
Quetzalcoatl, however, has other plans, and he instead proposes a bet. He doesn’t want to remake humanity, knowing that the told that will be used to close the gate is made up of obsidian, which will burn not just monsters but also gods, he decides to send a human to do it. He wants the worst human being on the planet to do the job, and if he succeeds, he will spare humanity. Quetzalcoatl will blood sacrifices of Tezcatlipoca, which would mean the end of the latter. Tezcatlipoca agrees on the condition of the Yaotl; his emissary will guide the chosen human.
Izel and Nelli, who are weaver, encounter survivors or the recent rampage in their town Uxmal. There is a rumor in the city that they need to make a sacrifice to protect the town from Mictlantecuhtli’s wrath. The elders of the town conclude that Izel will be sacrificed, but Nelli volunteers to die instead of him.
When the truth comes out, Izel runs to offer his blood before Nelli is sacrificed at sunrise. However, he fails to reach on time, and her sister is sacrificed. He is disturbed by her sister’s death and decides to commit suicide. When he jumps into a pit, his head is hit on the way down, and the blood summons a god. Yaotl rescues him, and Izel becomes the gods’ gift to humanity. It is an exciting situation for Izel, who no longer wants to live but has to carry the burden of his sister’s death and save the world.