Futaro has led five quintuplets to the point where they can graduate and pursue their own dreams. Now, finally, they had reached their final school festival. Having decided to make this occasion one to remember, Futaro searches for his feelings for the five quintuplets.

The year is 2027, and the city of Kyoto has undergone tremendous technological advancement. Within the city lives Naomi Katagaki, a socially awkward and introverted boy with a love for books, and Ruri Ichigyou, a girl with a cold personality who is often blunt with people, but shares his love for reading. Despite having similar interests, Naomi is afraid to approach Ruri due to her unfriendly nature. One day, as Naomi goes out for a walk, a crimson aurora pierces through the sky for a brief moment before vanishing. Shortly after, he sees a three-legged crow and a mysterious hooded man who reveals himself to be Naomi from 10 years in the future, explaining that he has come to change an imminent tragic event that happens to Ruri shortly after they start dating. Initially taking his words with a grain of salt, present-day Naomi follows his future self's instructions and starts getting closer to Ruri, determined to save her. Hello World focuses on the present Naomi alongside himself from 10 years into the future. With the help of his future self, Naomi begins his preparations to save Ruri. Will he be able to change the future? [Written by MAL Rewrite]

Kohachi Inugami, a detective who specializes in the occult, arrives at a remote village in the Japanese countryside, tasked by a hostess at a local inn to investigate a string of incidents involving rotting and mutilated livestock corpses that have been appearing for seemingly no reason. While surveying, Inugami notices a peculiar young boy working in the fields. Evaded by his peers and called "Dorotabou" for his stench, the young farmhand is surprised that anybody would take an interest in him. Inugami, piqued with curiosity, enlists Dorotabou in helping him with the investigation, despite scorned looks from the villagers. Unbeknownst to Dorotabou, this investigation will reveal a strange new world to him—one of the beast-like entities known as Kemono existing in tandem with humans—along with breathing new purpose into his previously empty life. [Written by MAL Rewrite]

Amatsuyu "Jouro" Kisaragi is a completely average second-year high school student who has two dates over one weekend⁠—with the student council president Sakura "Cosmos" Akino on Saturday, then with his childhood friend Aoi "Himawari" Hinata on Sunday. Sadly for Jouro, both girls proclaim their love for his best friend Taiyou "Sun-chan" Ooga, the ace of the baseball team. Accepting each of their requests for advice and guidance, he is now responsible for helping the two girls win the heart of the same guy. Unbeknownst to his friends, Jouro's friendly and obtuse image is all but a ruse designed to cast himself as the clueless protagonist of a textbook romantic comedy. A schemer under his cheery facade, he makes the best of this unexpected turn of events with a new plan: get Sun-chan to fall for either Cosmos or Himawari and take the other as his own prize. But Jouro's last-ditch effort is threatened by the gloomy, four-eyed Sumireko "Pansy" Sanshokuin, who surprises Jouro with not only her knowledge of his secret personality but also a confession to the true self he hid for all this time. Stuck in this hilariously messy situation, each of the five students must navigate countless lies, traps, and misunderstandings to come out on top. [Written by MAL Rewrite]