Ani ga Imouto de Imouto ga Ani de.

Twins Hikaru and Youta are an odd pair. Youta loves to cook and help out his family while Hikaru is a dark girl whose own family find her on the creepy side. Their everyday life involves Youta cooking and doting over his sister with Hikaru clinging on him. Then, on their birthday, their life changes. Youta learns that he is not related to Hikaru by blood and, while chasing after her, they both get hit by a car. When they wake up they find out that their lives have taken an unexpected turn. (Source: Mangafox)