The Japanese call them hikikomori - people who’ve become so socially withdrawn that they refuse to leave their homes for weeks and even months at a time. Sasami Tsukuyomi has been attempting to pass her first year of high school despite being a shut in. Fortunately, her older brother Kamiomi happens to be a teacher at the school she is supposed to attend. With the use of the “Brother Surveillance Tool” she can view the outside world via her computer. Theoretically it should be helping her adjust to interfacing with people again... Instead, it's giving her an up close and personal view of the very odd Yagami sisters who have various types of “interest” in Kamiomi. It looks like Sasami will have to take off her pajamas and go out into the “real” world to set things straight in Sasami-san@Ganabaranai!
The fun begins. Sasami is an overly spoiled, overly introverted girl with nothing better to do than to spy on her big brother's life. Things begin to liven up when she finds out he has given the chocolate she got for him to another girl.
After noticing the large number of absentees at school, Tsurugi and the other Yagami sisters find out that a game called "Yamato No Orochi" is responsible. While using Sasami's impressive collection of PC's, and with Sasami attempting to sabotage them along the way, they all suddenly get sucked into the game world and find that there's something amiss.
Sasami suddenly grows a third arm, and while searching for an answer to her extra limb dilemma she instead discovers the true origins of the Yagami sisters. The strange relationship between Sasami and her big brother is further explored, detailing their recent troubles with the rest of their family,
A dazed Sasami stumbles into her brother's room and finds what she thinks is a naughty DVD, but soon realizes that it is instead a report detailing the Yagami Sister's surveillance of every move she makes. The odd thing is, Sasami can't remember doing any of the things on film.
Sasami wants to use Kagami as a demo-friend, in order to make others view her as more likeable. Little does she know, being friends with Kagami is dangerous to herself as well as Kagami.
Sasami meets her long dead mother on the street, and convinced that she's come back, spends the day shopping with her. Little does she know, her priestess mother has something else in mind: returning Sasami to the shrine by any means possible.
Sasami's mother has captured both Sasami herself as well as her dear brother. In a bid to restore order to this world, Sasami's mother demands something from Sasami that she is unwilling to accept.
Sasami has secluded herself in her room during spring break, and fearing major consequences for the rest of the world, the Yagami sisters attempt to find their way through Sasami's powerful barrier.
Tomamo-no-Mae carries with her a big secret: she possessed a young Sasami and used her power to change the past. Sasami takes an unwelcome trip down memory lane in order to find out how to stop Tamamo from going further.
As Sasami's second year starts, she learns a frighteningly embarrassing secret. A class trip to a shrine is announced, but a bedridden Sasami is unable to attend. Instead, she uses her power in less than ethical ways...
Sasami's complications with Jou continue, as a friendly invite to a festival drives Kagami mad with jealousy. Sasami must smooth things over to avoid any further circumstances.
Jou feels betrayed after realizing the bond between Sasami and Kagami, and begins to put her plan into action. The prize is Tamama's power, and Jou will stop at nothing to get what she needs. Don't miss the exciting conclusion of Sasami-san@Ganbaranai!