Drift peacefully into Neo Venezia, a city on the planet Aqua (formerly known as Mars). By the 24th century, humans have found a way to colonize the previously uninhabitable planet. As futuristic as that sounds, Neo Venezia is still teeming with rustic beauty; gondolas on wide canals and waterways are the main mode of transportation. The city itself is a faithful replication of Manhome's (the planet formerly known as Earth) Venice. To make sure that residents and tourists alike get the most from Neo Venezia's many wonders, companies offering guided tours via gondola were formed, one of which is named Aria Company. This is the workplace of Akari Mizunashi, a free spirited teenager from Manhome who is now a novice Undine (the title given to tour guides). Join Akari as she becomes intimately acquainted with other Undine, tourists, Neo Venezia's residents, and even the city itself, learning many valuable life lessons along the way, such as the wonderful truth that there are such things as manmade miracles.

As Mikado Ryuugamine continues to purge the Dollars from within in accordance with his warped sense of justice, Masaomi Kida hopes to bring his friend back to his senses by bringing the Yellow Scarves together once more. Little do they know that a far more dominant force is about to enter their struggle for power, one that their friend Anri Sonohara is all too familiar with. Meanwhile, the group that has gathered at Shinra Kishitani's apartment realizes that they are on the brink of something life-changing, an event that will throw Ikebukuro into a spiral of confusion. Their anxiety is realized when reports of Celty's head being found in public start to appear all over the news as Kasane Kujiragi begins to make her move. Gone are the brief periods of tranquility as the current turmoil sets the stage for one final performance in this thrilling conclusion to the story of Ikebukuro's finest. [Written by MAL Rewrite]

Although peace has finally returned to Ikebukuro, many of the odd occurrences have become common sights around the city. One such case is the police's constant pursuit of Celty Sturluson, the Headless Rider. Moreover, someone has placed a large bounty on her, igniting the motivation of gang members all over to begin searching for the supernatural creature as well. Meanwhile, Mikado Ryuugamine is approached by Aoba Kuronuma, a mysterious underclassman with unknown intentions, who reveals that he knows Mikado's true identity. But Ikebukuro's state of tranquility is short-lived, as a new threat appears in the form of a murderer who goes by the pseudonym "Hollywood," known for wearing a different mask each time they commit a crime. As the various events taking place prove to be connected yet again, Ikebukuro is thrown into another conflict that threatens to engulf the entire city in chaos. [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]