Sister Princess (シスター・プリンセス ,Shisutā Purinsesu?) is a popular Japanese bishōjo series authored by Sakurako Kimino and illustrated by Naoto Tenhiro. It began as a serialized light novel series in 1999. In 2001, a manga series and a bishōjo game for the Sony PlayStation were released. Sequels to the game were released for the PlayStation and Game Boy Advance. Sister Princess was also adapted into a Japanese anime television series.

Source: Wikipedia