Muaisou na Futago no Ane ga, Nazeka Ore to Naka no Yoi Futago no Imouto no Furi wo Shiteiru Hanashi

His childhood friends are a set of twins, one who is doting and kind, and the other is stone-faced and awkward. He is convinced the latter girl hates him... but she seems to be messing up her cues instead, and her intentions are not what he expected them to be...