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!

Yukino Miyazawa is the female representative for her class and the most popular girl among the freshmen at her high school. Good at both academics and sports on top of being elegant and sociable, she has been an object of admiration all her life. However, in reality, she is an incredibly vain person who toils relentlessly to maintain her good grades, athleticism, and graceful appearance. She wants nothing more than to be the center of attention and praise—which is why she cannot stand Souichirou Arima, the male representative for her class and the only person more perfect than her. Since the first day of high school, she has struggled to steal the spotlight from her new rival but to no avail. At last, on the midterm exams, Yukino gets the top score and beats Souichirou. But, to her surprise, he congratulates her on her achievement, leading her to question her deceptive lifestyle. When Souichirou confesses his love to Yukino, she turns him down and gloats about it at home with only a hint of regret. But the very next day, Souichirou visits Yukino house to bring her a CD and sees her uninhibited self in action; now equipped with the truth, he blackmails her into completing his student council duties. Coerced into spending time with Souichirou, Yukino learns that she is not the only one hiding secrets.

Ever since Rakurou Sunraku Hizutome started to play the extremely popular virtual reality game Shangri-La Frontier, he has truly fallen in love with it. Sunraku has quickly made a big name for himself by fighting two of the seven unique, nearly unbeatable monsters, which is unthinkable for most players. To progress the game's story, he sets out on an adventure with his leporine guide, Emul, to acquire a magic operation unit from an ancient workshop. Though Sunraku breezes through this quest alongside his clanmates Towa Arthur Pencilgon Amane and Kei OiKatzo Uomi, there seems to be an ulterior motive as to why the two of them decided to help Sunraku in the first place. Nevertheless, Sunraku gains valuable knowledge and allies, critical for his advancement in the game. By seeking out powerful enemies and unraveling the inner workings of the game's world, Sunraku may just change Shangri-La Frontier forever.

It has been six months since Yoshiki Tsujinaka's best friend, Hikaru Indou, went missing in the mountains and returned a week later with no recollection of what had transpired. Certain that it is not the Hikaru he knows who came back, Yoshiki finally asks Hikaru about it. Suddenly, Hikaru reveals his true monstrous form and begs Yoshiki to keep it a secret, as he does not want to kill him. Despite his paranormal nature, Hikaru seems almost innocent, full of childlike wonder and eager to experience the summer heat, the countryside, and all kinds of other things in a human body for the first time. And for Yoshiki, it matters little if Hikaru is a fake relying on stolen memories—as long as he never leaves again. As Yoshiki desperately clings to Hikaru in his intense grief, it becomes increasingly clear that something dangerous and supernatural may have descended from the mountains into their village.