Ishiyama High is a school populated entirely by delinquents, where nonstop violence and lawlessness are the norm. However, there is one universally acknowledged rule—don't cross first year student Tatsumi Oga, Ishiyama's most vicious fighter. One day, Oga is by a riverbed when he encounters a man floating down the river. After being retrieved by Oga, the man splits down the middle to reveal a baby, which crawls onto Oga's back and immediately forms an attachment to him. Though he doesn't know it yet, this baby is named Kaiser de Emperana Beelzebub IV, or "Baby Beel" for short—the son of the Demon Lord! As if finding the future Lord of the Underworld isn't enough, Oga is also confronted by Hildegard, Beel's demon maid. Together they attempt to raise Baby Beel—although surrounded by juvenile delinquents and demonic powers, the two of them may be in for more of a challenge than they can imagine.

A new era of exploration begins with the sudden appearance of a new continent known as Magmell. Magmell's vast trove of never-before-seen natural resources spurs on the exploration of its vast landscape. However, the unknown is not always docile. In order to sustain the expeditions, people known as "anglers" specialize in dealing with Magmell's dangerous wildlife. One such angler is the highly-skilled and experienced Inyou, who performs search and rescue operations for clients with the help of his assistant, Zero.

Saki Uno is an average 15-year-old girl with a side hustle as a member of the exceptionally unpopular idol duo Magical Twins. Despite this, she absolutely loves the time she spends with her best friend Sakuyo Mikage as she strives to become closer with her childhood crush, Sakuyo's brother Mohiro. Her peaceful life, however, unravels when she finds a yakuza-looking thug trying to enter her house. Forced to invite him inside, Saki learns that her mother used to be a demon fighting Magical Girl, and that her brutish guest is actually a mascot named Kokoro-chan looking to recruit a replacement. Dumbfounded and skeptical, Saki is hesitant accept the request until Kokoro-chan reveals that Mohiro is a target of some cute, squirrel-tailed demons. Rushing to his side, Saki's overwhelming desire to save Mohiro activates her Love Power, and a daring confession awakens her as a Magical Girl. However, because her body is not suitable for combat, Saki's transformation turns her into a muscle-bound man clad in a pretty dress. Now, as a fully-fledged Magical Girl, Saki must team up with Sakuyo to protect the love of her life from the fluffy, demonic menaces that run rampant in her world.

Ancient Japan is under attack by powerful beings called "Kamikui," and it is up to the "Oni" and his band of eight beautiful female warriors to stop them. Each of these girls have unique skills, abilities, and personalities. They partner themselves with the Oni, Jin, to stop the miasma of darkness sweeping across Japan. Onigiri follows the escapades of Jin and his merry companions as they strengthen their bonds and fend off the demonic invasion.