Kazuki Yotsuga is your regular average nerd in high-school, except he isn't smart. He has this website which relates to his visions that only he can see. His visions are about robots who keep fighting each other battle after battle. One day he is sent to a parallel world where these visions exist and he joins a company to fight back against the devious RaRa, who want to take over the world. (Source: ANN)

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.

Second part of Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka IV.

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.