Ainz Ooal Gown, the undead sorcerer formerly known as Momonga, has accepted his place in this new world. Though it bears similarities to his beloved virtual reality game Yggdrasil, it still holds many mysteries which he intends to uncover, by utilizing his power as ruler of the Great Tomb of Nazarick. However, ever since the disastrous brainwashing of one of his subordinates, Ainz has become wary of the impending dangers of the Slane Theocracy, as well as the possible existence of other former Yggdrasil players. Meanwhile, Albedo, Demiurge and the rest of Ainz's loyal guardians set out to prepare for the next step in their campaign: Nazarick's first war… Overlord II picks up immediately after its prequel, continuing the story of Ainz Ooal Gown, his eclectic army of human-hating guardians, and the many hapless humans affected by the Overlord's arrival.

The Soul Translator is a state-of-the-art full-dive interface which interacts with the user's Fluctlight—the technological equivalent of a human soul—and fundamentally differs from the orthodox method of sending signals to the brain. The private institute Rath aims to perfect their creation by enlisting the aid of Sword Art Online survivor Kazuto Kirigaya. He works there as a part-time employee to test the system's capabilities in the Underworld: the fantastical realm generated by the Soul Translator. As per the confidentiality contract, any memories created by the machine in the virtual world are wiped upon returning to the real world. Kazuto can only vaguely recall a single name, Alice, which provokes a sense of unease when mentioned in reality. When Kazuto escorts Asuna Yuuki home one evening, they chance upon a familiar foe. Kazuto is mortally wounded in the ensuing fight and loses consciousness. When he comes to, he discovers that he has made a full-dive into the Underworld with seemingly no way to escape. He sets off on a quest, seeking a way back to the physical world once again.

Violent misfortunes frequently occur around 16-year-old Yuuta Okkotsu, a timid victim of high school bullying. Yuuta is saddled with a monstrous curse, a power that dishes out brutal revenge against his bullies. Rika Orimoto, Yuuta's curse, is a shadow from his tragic childhood and a potentially lethal threat to anyone who dares wrong him. Yuuta's unique situation catches the attention of Satoru Gojou, a powerful sorcerer who teaches at Tokyo Prefectural Jujutsu High School. Gojou sees immense potential in Yuuta, and he hopes to help the boy channel his deadly burden into a force for good. Yet Yuuta struggles to find his place among his talented classmates: the selectively mute Toge Inumaki, weapons expert Maki Zenin, and Panda. Yuuta clumsily utilizes Rika on missions with the other first-year students, but the grisly aftermath of Rika's tremendous displays of power draws the interest of the calculating curse user Suguru Getou. As Getou strives to claim Rika's strength and use it to eliminate all non-jujutsu users from the world, Yuuta fights alongside his friends to stop the genocidal plot.

The Moon Festival is Tootsuki Academy's annual gourmet gala, where students compete against each other to earn the most profit through selling their cuisine of choice. But for Souma Yukihira, it is also his first opportunity to challenge the Elite Ten, the supreme council that rules over the academy. However, this is only the beginning of Souma's war against the Elite Ten; a nefarious plot is underway that will provide Souma with the challenge he desires but will also shake the very foundations of Tootsuki Academy itself.