The rare and inexplicable Puberty Syndrome is thought of as a myth. It is a rare disease which only affects teenagers, and its symptoms are so supernatural that hardly anyone recognizes it as a legitimate occurrence. However, high school student Sakuta Azusagawa knows from personal experience that it is very much real, and happens to be quite prevalent in his school. Mai Sakurajima is a third-year high school student who gained fame in her youth as a child actress, but recently halted her promising career for reasons unknown to the public. With an air of unapproachability, she is well known throughout the school, but none dare interact with her—that is until Sakuta sees her wandering the library in a bunny girl costume. Despite the getup, no one seems to notice her, and after confronting her, he realizes that she is another victim of Puberty Syndrome. As Sakuta tries to help Mai through her predicament, his actions bring him into contact with more girls afflicted with the elusive disease. [Written by MAL Rewrite]

In Tokyo's downtown district of Ikebukuro, amidst many strange rumors and warnings of anonymous gangs and dangerous occupants, one urban legend stands out above the rest—the existence of a headless "Black Rider" who is said to be seen driving a jet-black motorcycle through the city streets. Mikado Ryuugamine has always longed for the excitement of the city life, and an invitation from a childhood friend convinces him to move to Tokyo. Witnessing the Black Rider on his first day in the city, his wishes already seem to have been granted. But as supernatural events begin to occur, ordinary citizens like himself, along with Ikebukuro's most colorful inhabitants, are mixed up in the commotion breaking out in their city. [Written by MAL Rewrite]

Otonashi awakens only to learn he is dead. A rifle-toting girl named Yuri explains that they are in the afterlife, and Otonashi realizes the only thing he can remember about himself is his name. Yuri tells him that she leads the Shinda Sekai Sensen (Afterlife Battlefront) and wages war against a girl named Tenshi. Unable to believe Yuri's claims that Tenshi is evil, Otonashi attempts to speak with her, but the encounter doesn't go as he intended. Otonashi decides to join the SSS and battle Tenshi, but he finds himself oddly drawn to her. While trying to regain his memories and understand Tenshi, he gradually unravels the mysteries of the afterlife. [Written by MAL Rewrite]

Jinta Yadomi is peacefully living as a recluse, spending his days away from school and playing video games at home instead. One hot summer day, his childhood friend, Meiko "Menma" Honma, appears and pesters him to grant a forgotten wish. He pays her no mind, which annoys her, but he doesn't really care. After all, Menma already died years ago. At first, Jinta thinks that he is merely hallucinating due to the summer heat, but he is later on convinced that what he sees truly is the ghost of Menma. Jinta and his group of childhood friends grew apart after her untimely death, but they are drawn together once more as they try to lay Menma's spirit to rest. Re-living their pain and guilt, will they be able to find the strength to help not only Menma move on—but themselves as well? [Written by MAL Rewrite]