High school student Aoi Aioi lives with her elder sister, Akane, after a tragic accident took their parents away 13 years ago. Because Akane has since been taking care of her single-handedly, Aoi wants to move to Tokyo after her graduation to relieve her sister's burden and pursue a musical career, inspired by Akane's ex-boyfriend Shinnosuke "Shinno" Kanamuro. Shinno was part of a band until he left for Tokyo to become a professional guitarist after the sisters' parents passed away, and he was never to be seen again.
Unaired special of “Himouto! Umaru-chan” included with the manga’s tenth compiled volume. Realizing it is Taihei's birthday, Umaru asks Nana for advice on what to do for him. Umaru decides to act like an ideal sister and spend time with Taihei, only to discover that he prefers her the way she is. Later, as the girls begin their summer vacation by going to a swimming pool, Umaru wonders if she should stop putting on an act in front of her friends and reveal that she, Komaru, and UMR are the same person. As Umaru becomes conflicted over what will happen if she tells everyone, her friends assure her that she doesn't need to reveal her secrets if it'd just make her suffer. Relieved by the support of her friends, Umaru makes the decision to continue hiding her secret.
Unaired special of “Himouto! Umaru-chan” included with the manga’s seventh compiled volume. After being tempted by a pillow on the television shopping channel, Umaru has a dream reminding her to appreciate the pillow she has. The next day, Umaru goes with Sylphnford to the convenience store where she tries to win a lottery prize. Later, Umaru and Taihei go wild at a yakiniku restaurant, unaware that Nana is at the next table over. At the start of October, Umaru and Kirie get into the Halloween spirit early, dressing up in costume and trying various pumpkin-based snacks. Afterwards, Umaru decides to fake a fever in order to skip school, only to be overcome by guilt.
