Three Sisters' Story (三姉妹 Sanshimai, Three Sisters) is a adult bishōjo visual novel for the PC by Sakura Soft. It was translated to English by JAST USA.
The gameplay is standard for a visual novel. The player reads text at the bottom of the screen, which is accompanied by static images. A number of choices are made during the course of the game, letting the player direct the main character through the plot, and into sexual encounters with Yuki, Emi or Risa, the three main female characters, as well as with a number of other females.
Source: Wikipedia, "Three Sisters' Story", available under the CC-BY-SA License.