"Aneimo (Square Sisters)" follows high school student Takumi, whose life changes when his father brings home two girls, Saori and Yui, introducing them as new family members despite no blood relation. Living next door to his childhood friends Mizuki and Satsuki, Takumi navigates growing romantic tensions and harem-like dynamics amid confusion and budding affections. As relationships deepen, the story explores themes of unexpected family bonds and youthful desires in a classic romance setup.