Responsible Taihei has to deal with his lazy little sister, Umaru, who trashes his apartment and throws tantrums to get manga and junk food.

Taihei comes home to a complete stranger: Umaru’s public face. She’s cleaned the apartment and hidden her games to be able to invite her classmate and neighbor, Ebina, over.

Umaru’s sulky, glaring classmate, Motoba, has unexpectedly shown up at her door… while she’s wearing her hood! Is her secret out?

Umaru, aka UMR, is a force to be reckoned with in the arcade. She’s invited to participate in a fighting game championship only to bump into her school rival, Tachibana.

Summer vacation means hours at the arcade! Umaru instructs in the fine art of enjoying summer like a (lazy) pro. Later, Taihei endures another typical day at work.

Taihei and Umaru experiment with free time and personal space in their little apartment, and playing “The Game of Life” hits too close to home for them all.

People in his office have seen Taihei walking home and going shopping with a hot girl! His coworker comes over for a visit to see this so-called “sister” for himself.

In the Doma household, winter means lazy days beneath the kotatsu! Umaru reflects on her interesting year while Taihei tries to collect on a promise she made to him.

It’s Valentine’s Day! Kirie burns cookies, Ebina attempts to make chocolate, and Umaru continues to offload food prep to Taihei.

Umaru gets sick, but it’s a good thing her germs are as lazy as she is! Sadly, her germs show her brother no mercy. Later, Taihei remembers a day at the arcade, 10 years ago.

Umaru and Ebina discover that their appetites match, the council in Umaru’s head furiously debates about the perfect snack, and Taihei tries to get Kirie excited for summer.

In this last episode of the season, Umaru might have to reveal her secret when her separate circles of friends come together during a much anticipated trip to the beach!

Umaru Doma's life continues with an evening filled with video games... and no big brother in sight! Later, Umaru and her friends end up playing an intense game of soccer.

Taihei invites his coworkers over for dinner after work, and one of them, Alex, catches Umaru's attention. Why does this guy seem so familiar, and what's his deal with anime?

Alex interrupts Kirie and Umaru's afternoon to play a dating sim game. Kirie finds herself identifying with the main character. Later, Umaru discovers an addictive new game.

Umaru spends Christmas evening with her friends, and Sylphyn remembers a childhood Christmas wish. On New Year's morning, Umaru receives a suspicious gift from Taihei.

Taihei leaves for a business trip with his co-workers. While his boss Kanau thinks of a way to spend time with him, Taihei has his hands full with a vacation-happy stowaway.

While visiting Umaru, Kirie’s secret aspiration is found out! Will Umaru’s encouragement be enough to help Kirie overcome her self-doubt?

Umaru and the girls head out to spend a fun day at the amusement park, but Kirie is having a few struggles. Will the day end up a total disaster?

Umaru and the gang have a spontaneous get-together, but when things don't go as expected, hilarity ensues.

After Bomba gives Taihei one of his old cameras, Taihei spends sometime reconnecting with Umaru. Later, the tension between Hikari and Umaru increases.

Sylphin invites UMR over to her house, where a slight misunderstanding leads to some awkwardness. Later on, Umaru seems to have found a weakness in Hikari’s armor.

Kirie devises a new plan to bring Ebina and Taihei closer. However, Taihei might have a couple to many little sisters fighting for his attention already.

It's the end of the year, and everyone is figuring out what Christmas gifts to get their loved ones. Can Umaru and the others find the perfect presents?