Several hundred years ago, humans were nearly exterminated by giants. Giants are typically several stories tall, seem to have no intelligence, devour human beings and, worst of all, seem to do it for the pleasure rather than as a food source. A small percentage of humanity survived by enclosing themselves in a city protected by extremely high walls, even taller than the biggest of giants. Flash forward to the present and the city has not seen a giant in over 100 years. Teenage boy Eren and his foster sister Mikasa witness something horrific as the city walls are destroyed by a super giant that appears out of thin air. As the smaller giants flood the city, the two kids watch in horror as their mother is eaten alive. Eren vows that he will murder every single giant and take revenge for all of mankind.
Akihito Kanbara is a high school sophomore in the literature club who believes himself to be a "Meganest", and although he appears to be human, he is actually half Yōmu, which makes him invulnerable to wounds, due to the fact that he can heal so quickly, and also immortal. One day, Akihito meets freshman Mirai Kuriyama when it appears as if she is about to attempt suicide by jumping off of the school rooftop. Mirai is isolated because of her ability to manipulate blood, which is considered heresy even among other members of the underworld, so she is shunned. Soon after Akihito saves Mirai, disturbing events begin to arise.
Humans live in the world of Assiah, demons in Gehenna. The two dimensions are not meant to interfere with each other, but demons still possess creatures in Assiah in spite of this. The humans who can fight these demons are known as exorcists. Rin Okumura is a boy who bears the curse of being Satan's illegitimate son. His foster father sacrificed himself to save him from demons. To avenge his foster father's death as well as to prove himself, Rin decides to follow the path of an exorcist.
In the year 2071, the Far East is ruled by angry gods. 20 years ago unknown life forms called “Oracle cells” begin their uncontrolled consumption of all life on Earth. Humanity both fears them and reveres them as "aragami." They are immune to all weapons and the mankind's numbers continue to dwindle. The last bastion of hope is the newly developed "God Arcs" weapons that utilize Oracle cells to fight back. The weapons wielders band together into an elite force dubbed "God Eaters."
In the second season of Noragami the main focus is on Bishamon, god of war. She has many shinki due to her being unable to abandon spirits attacked by Ayakashi. She has a large group of shinki with her as leader, causing her trouble as she sometimes cannot tend to all of them properly, especially when one of them gets sick or is in pain. She has a strong hate for Yato, as a dark past binds the two of them. How will the horrifying events dated hundreds of years ago in combination with current evil happenings affect Yato and Yukine?