Koyama Yuzu is running an antique shop. Mayu, a cat god (nekogami), is living off Yuzu and leads an idle life playing games. Lots of other gods visit Mayu and enjoy merrymaking.

Hacka Dolls are AI that scan a person in order to tailor news recommendations and information to their users. These widespread, personalized robots have served many citizens, from government officials to professional sports players. A severe drop in quality leads to the production of three substandard Hacka Dolls. Due to their personality defects, they are sent to Earth, tasked with advancing humanity in whatever way they can. Whether it be encouraging a fujoshi to sell a doujinshi at Comiket or performing in an idol group, the three dolls will complete any task as long as it abides by their moral compass. Despite their shortcomings, they take their mission very seriously and always try their best to assist everyone with incredible enthusiasm.

Masahiro Setagawa is a hopeless teenager who is often used by the neighborhood bullies as an errand boy. Defenseless, Masahiro knows that nobody will ever save him. However, his life drastically changes when he meets Kousuke Ooshiba, a man known as the "Bear Killer," who takes down neighborhood gangs. A year later, Masahiro and his former friend, Kensuke Ooshiba, attend high school, only to find that Kousuke is their math teacher. While the three grow closer, Masahiro starts to view Kousuke as his "hero," and Kousuke develops an urging desire to protect Masahiro. However, their normal lives take a turn when Kensuke's childhood friend, Asaya Hasekura, returns, seeing Kensuke as more than just a friend, much to his surprise. Will the three boys be able to live a regular high school life? Or will forbidden love keep them apart forever?

Umaru Doma is a model student who has a hidden side: when she gets home each day, she puts on her hamster hoodie and turns into a sluggish otaku fond of junk food. As Umaru continues these daily antics, the friendship between her and her classmates—Nana Ebina, Kirie Motoba, and Sylphinford Tachibana—deepens, and more and more interesting events begin to unfold. Of course, these events give rise to numerous questions. What did Nana ask of Umaru's brother Taihei? Who is the mysterious girl with the diamond hairpin? And most important of all: why does this girl seem to know Umaru? These questions and more will be answered in Himouto! Umaru-chan R!