A squid-like creature, known as a Happian, leaves his home planet with the desire to spread happiness across the universe. He lands on Earth, but quickly finds himself in danger of captivity by its inhabitants. Fortunately, he is found by an unsmiling little girl named Shizuka Kuze, who feeds him and names him Takopii. Feeling indebted, Takopii decides to do everything in his power to bring a smile to her face. The task is easier said than done, however. Shizuka is bullied by her classmates, she does not have a father, and her mother is never home—though the gravity of these issues flies over the naive Takopii's head. Even so, Shizuka does have one source of happiness: her dog Chappy. The connection Shizuka and Chappy share only increases Takopii's desire to make the girl smile. While Takopii's attempts to lift Shizuka's spirits lead to unintended consequences, he is determined to take things into his own tentacles, test his understanding of human beings, and achieve his goal of spreading happiness.

Melphiera Marchalrayd, the daughter of a count, dedicates her time to researching the culinary possibilities of monster meat—a peculiar endeavor started by her late mother. By teaching the people of the Marchalrayd lands to prepare such exotic ingredients, Melphiera hopes to help stave off famine. Unfortunately, her unique tastes and intimate knowledge of monsters have led to her social isolation: few nobles interact with her willingly, disdainfully calling her the Voracious Villainess. When a monster attack erupts at a royal banquet—where Melphiera has been sent to find a husband—Aristide Rogier du Galbraith, the younger brother of the crown prince, leaps to her aid. Due to his terrifying skill in slaying monsters, Aristide has earned the title of Blood-Man Duke. Charmed by Melphiera's fearlessness and intriguing culinary prowess, Aristide soon declares his intent to propose. Together, Melphiera and Aristide, high society's most eccentric couple, strive to see beyond the cruel rumors and encourage each other's fascination with monsters and the art of preparing them.

High school first year Yuu Yuutani has always been a good girl, following the rules, helping out around her house, and generally going through life unnoticed. From afar, she reveres her upperclassman and the school's Public Decency Officer, Atori Mizutori, and desperately wants her attention. When she realizes that the best way to get Atori to notice her is to be a delinquent, she begins to dress differently: she dyes parts of her hair a bright red, wears clips on her ears to resemble piercings, and attaches jumbo erasers to her shoes to give them thicker soles. Despite Yuu's best efforts and even with the advice of her natural born delinquent friend Suzu Suzukaze, all of her plans to be a bad girl go awry. Still, Yuu manages to befriend Atori and pledges to spend as much time as possible together, not knowing there are others vying for Atori's attention. In the process, Yuu has also gained the attention of the school's self-proclaimed idol, Rura Ruriha, filling her once-invisible life with more attention than she may be able to handle.

Final season of Boku no Hero Academia.