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.

"The New Gate" is an online life-or-death game with tens of thousands of players. Thanks to Shin, the most skilled veteran player, the other players will finally be released from the game. Shin has killed the last boss and believes he is finally able to escape when he is blinded by a flash of mysterious light. He awakes to find himself in the game's world 500 years later! So begins a new chapter in the life of an unsurpassed legendary player!