Supersonic monkeys, vampires, talking fishmen, and all sorts of different supernatural monsters living alongside humans—this has been part of daily life in Hellsalem's Lot, formerly known as New York City, for some time now. When a gateway between Earth and the Beyond opened three years ago, New Yorkers and creatures from the other dimension alike were trapped in an impenetrable bubble and were forced to live together. Libra is a secret organization composed of eccentrics and superhumans, tasked with keeping order in the city and making sure that chaos doesn't spread to the rest of the world. Pursuing photography as a hobby, Leonardo Watch is living a normal life with his parents and sister. But when he obtains the "All-seeing Eyes of the Gods" at the expense of his sister's eyesight, he goes to Hellsalem's Lot in order to help her by finding answers about the mysterious powers he received. He soon runs into Libra, and when Leo unexpectedly joins their ranks, he gets more than what he bargained for. Kekkai Sensen follows Leo's misadventures in the strangest place on Earth with his equally strange comrades—as the ordinary boy unwittingly sees his life take a turn for the extraordinary.

Veyron City—a mega-floating metropolis created from the discovery of new energy sources. Shuu, a young man who owns and operates a small business in the area, leads a meager life due to his reckless spending. Kisara, a girl who visits Shuu's office and home because she is constantly concerned about him. She works while attending high school in Veyron City, doing everything from clerical work to housework. Ayano, Shuu's ex-girlfriend and a senior colleague at the corporation he had previously worked for, is also worried about him. Thus begins the slapstick romantic comedy of three people in a slightly unusual relationship that takes place on an artificial island in the Pacific Ocean.

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. [Written by MAL Rewrite]

Ryuuto Kashima is a gloomy high schooler. As part of a punishment game, he was forced to confess to Runa Shirakawa, a girl from the top of the school caste who was admired by everyone. They ended up going out for the unexpected reason of "Err, I'm free now so..." but Ryuuto ends up following and eavesdropping on Runa being confessed by a handsome soccer club member, and Runa bringing Ryuuto, whom she had just begun dating, to her own room as a matter of course. They have different friends and ways to have fun, and they are different in almost every way. Nonetheless, they begin to relate with each other after being surprised by their differences every day and accepting them.