Sasami Tsukuyomi is a hikikomori, someone who's become so withdrawn socially that they refuse to leave home for weeks and even months at a time. Fortunately for Sasami, her brother Kamiomi teaches at the high school Sasami should be attending; and with her "Brother Surveillance Tool," which lets her view the outside world via her computer, she's trying to adjust to interfacing with people again. What her computer mainly does, however, is allow her to spy on her brother's interactions with the three very odd Yagami sisters, who inexplicably seem to have had their ages reversed and have various types of "interest" in Kamiomi. And then things start to get really weird… Magical powers? Everything turning into chocolate? Is life via the web warping Sasami's brain, or is it the universe that's going crazy? Sasami may have to take off her pajamas and go out into the "real" world to set things straight in SASAMI-SAN@GANBARANAI!