Naota Nandaba is an ordinary sixth grader living in a city where nothing amazing ever seems to happen. After his brother Tasuku leaves town to play baseball in America, Naota takes it upon himself to look after everything Tasuku left behind—from his top bunk bed to his ex-girlfriend Mamimi Samejima, who hasn't stopped clinging to Naota since Tasuku left. Little does Naota know, however, that his mundane existence is on the verge of being changed forever: enter Haruko Haruhara, a Vespa-riding, bass guitar-wielding, pink-haired psychopath whose first encounter with Naota leaves him with tire tracks on his back and a giant horn on his head. Though all he wants is some peace and quiet, when Haruko takes up residence at his parents' home, Naota finds himself dragged into the heart of the greatest battle for supremacy that Earth—and quite possibly the entire universe—has ever seen. [Written by MAL Rewrite]

In Ikebukuro, the lives of its citizens continue intertwining with each other as if their fates are predestined. Mikado Ryuugamine is now one step closer to his goal of living an exciting life, and in turn, delves deeper into the darker side of Ikebukuro. After gaining absolute control over a former rival, he uses his newfound power as he pleases, purging the Dollars from the inside to mold it into the ideal organization. This proves to be as challenging as it sounds as Mikado must now deal with unwanted outside interference, most notably a re-emerging and dearly missed friend. Meanwhile, Izaya Orihara still has some schemes up his sleeve, although a rival information exchange center has proven to be quite the hindrance, lurking within everyone’s favorite downtown district. Undoubtedly, sooner or later, chaos will strike again. [Written by MAL Rewrite]

Akari Mizunashi dreams of life after attaining her goal of becoming a Prima Undine, but upon waking realizes that she might not actually have the confidence to run Aria Company on her own. Wary of the future, she seeks advice from her mentor Alicia Florence—one of the three great "Water Fairies" of Neo-Venezia. Much to Akari's surprise, Alicia reveals her own struggles of the past, but also shares the steps she took in overcoming her self-doubt of running the company and taking on an apprentice. Finding solace in her teacher's words, Akari prepares to embrace whatever trials she must overcome on her path toward achieving her dreams.

Known for her semblance to the Sadako character of The Ring series, Sawako Kuronuma is given the nickname "Sadako" and misunderstood to be frightening and malicious like her fictional counterpart, despite having a timid and sweet nature. Longing to make friends and live a normal life, Sawako is naturally drawn to the cheerful and friendly Shouta Kazehaya, the most popular boy in her class. From their first meeting, Sawako has admired Kazehaya's ability to be the center of attention and aspires to be like him. When Kazehaya organizes a test of courage for the entire class and encourages her to attend, Sawako sees this as an opportunity to get along with her classmates, starting with Ayane Yano and Chizuru Yoshida. Through each new encounter and emotion she experiences, Sawako believes that meeting Kazehaya has changed her for the better. Little does Sawako know, her presence has also changed Kazehaya.