We now know why Spring was always blaming herself for hurting Yuu. He hadn't know that his mother had knelt down on her knees to his sisters begging them to believe what Yuu said "that he was falsely accused, that it was the truth." When he tried to run away from his sisters, to his room, Spring grabbed his leg, causing him to fall on the stairs and lose consciousness,

結局、この姉妹は本当の両親同様にクズで救いのない存在。本当に反省してるなら姉妹全員家から出て行けばいい。
しかしこの姉妹はバイトしてる感じはしないし奨学金を貰ってる感じもないし何処から学費や生活費が出てるんだろ？もしかして優の亡き母親の貯金とか生命保険とかを着服してるとか？