The year is 2027 in MegaTokyo, six years before the Knight Sabers will make their debut. Boomers (artificial humans) are still a relatively new advancement, and the implementation and integration of boomers into society is still a bit buggy -- sometimes fatally so. Whenever a boomer incident occurs, though, there is the Advanced Police, a special force trained to deal with boomer crimes. Leon McNichol is a rookie in the AD Police, and is just starting to become exposed to the horrors and tragedies one finds every day in MegaTokyo. He and his veteran partner, Gina Marceau, slowly learn about the ever-fading line that separates man from machine.

The ordinary life of 17-year-old otaku Hajime Nagumo is disrupted when he and his classmates are summoned to a fantasy world and tasked with saving mankind. While his classmates are gifted with impressive abilities useful in combat, Hajime is belittled for only gaining an inferior transmutation skill that lacks any real offensive power. During an expedition in the Great Orcus Labyrinth, Hajime is betrayed by one of his classmates, plummeting him to the bottom of an abyss. Though he survives the fall, Hajime is faced with menacing monsters and misfortunes that send him spiraling into a grim nightmare. Desperate to live and return home one day, he resolves to fight for his survival—only to meet an imprisoned vampire he names Yue, who is also seeking to escape the labyrinth. Taking an interest in him, Yue and a few others along the way accompany Hajime on his journey to find a way back home, while steadily transforming from commonplace to the world's strongest. [Written by MAL Rewrite]

One day, a city suddenly disappears. Takuya, a professional by-the-contract courier and lone wolf, meets Yuki, the only survivor from the city's extinction. The two rely on a message from Yuki's father, who was heard to be missing, and head toward the disappeared city, Lost. However, unexpected obstacles strike before the pair, with the reality especially shocking for Yuki. Before them are the feelings of those left behind, a mysterious group manipulating in the shadows, and unveiling the hidden conspiracy. Takuya and Yuki, who both were initially strangers, would deepen their bond during the journey and unravel the mystery of the Lost city. (Source: MAL News)

An adventurous wild mouse called Gamba travels with his friends to see the ocean but he finds an injured mouse and hears about the violence of white ferret Noroi. Gamba decides to help the mice suffering under Noroi's tyranny.