The Japanese call them hikikomori—people who've become so withdrawn socially that they refuse to leave their homes for weeks and even months at a time. For Sasami Tsukuyomi, who's attempting to pass her first year of high school despite being a shut in, it's more than just a word. Fortunately though, she lives with her older brother Kamiomi, who just happens to be a teacher at the school Sasami is supposed to attend....