Five years ago, gravity-defying bubbles with mysterious powers rained down upon the earth. After a huge explosion of uncertain origin, Tokyo became ground zero, with the city being enclosed in a gigantic bubble. As a result of this Bubble Fall phenomenon, the metropolis that was once the capital of Japan drowned in a gravity-bending sea; the government declared it a prohibited zone, and the residents abandoned it. Children orphaned by the Bubble Fall now squat illegally in Tokyo, partaking in dangerous parkour team battles across the city's dilapidated buildings. Hibiki—a talented ace in these games with the ability to jump between bubbles—claims he can hear sounds from the Tokyo Tower. Determined to uncover its mysteries, he sets off toward the source, but he falls into the waters below. A strange girl, whom he later nicknames Uta, saves him. But little does Hibiki know that Uta's appearance in his life will reveal the secrets behind the disastrous event that changed their world forever.

When Origami Tobiichi asks Shidou Itsuka out on a date, Shidou considers this his best opportunity to set the record straight and end their relationship. However, even with the help of the Ratatoskr crew, his attempts to break up with her fail; in fact, Origami gladly tolerates Shidou's humiliating requests and blunt comments! Shidou's unconventional mission incidentally complicates his relationship with Tooka Yatogami, and it seems that easing the tension is only possible by going on another date.

Mahiru Shirota firmly believes that simple is best and troublesome things should be avoided at all costs. It is troublesome to do nothing and regret it later—and this ideology has led the 15-year-old to pick up a stray cat on his way home from school. As he affectionately names the feline Kuro, little does he know that this chance meeting will spark an extraordinary change in his everyday life. One day, Mahiru returns home to find something quite strange: a mysterious young man he has never seen before. His subsequent panic results in the uninvited guest being exposed to sunlight and—much to Mahiru's shock—transforming into Kuro! Upon revealing himself as a mere lazy shut-in vampire, Kuro promises to leave once night falls. However, one disaster after another leads to Mahiru accidentally forming a contract with his new freeloader, dragging him into a life-threatening battle of supernatural servants and bloodthirsty beings that is anything but simple.

Some offices have stereotypical dynamics: the chauvinistic pig of a boss who never does any real work; the employees whose goal is to suck up to the boss; the ones whose lives seem perfect; and the individuals who have all the actual work pushed onto them. Retsuko the red panda is in the last group, as she stays late most nights to make up the work her coworkers are too lazy to do themselves. Her relief from the stress of her everyday life comes in the form of singing death metal at a local karaoke club. Night after night, Retsuko channels her grief into a microphone and considers the place to be her own personal sanctuary. But as she moves further away from her comfort zone and the ideas people have of her, she discovers that letting others into her world of death metal may not be such a bad thing.