Kashimashi ~Girl Meets Girl~ "Hajimete no Natsu Monogatari."

Based on the manga and anime series by Satoru Akahori of the same name.

The game's story begins on the outset of summer vacation. Hazumu's homeroom teacher Namiko Tsuki suggests Hazumu and her friends take a one-week trip to a small mountain village with a hot spring resort. Hazumu's grandparents reside in this town, and are two new characters introduced to the story. Three other female characters are introduced as possible love interests for Hazumu; two are the same age as her, and the third is the older landlady of the resort.

The goal of the game is to pair Hazumu up with one of the five female cast of characters. The gameplay's main system comes from Hazumu's indecisive personality. If the player shows more interest in a particular character, the other characters get annoyed that Hazumu is ignoring them, which is displayed in a tension meter. The more Hazumu ignores a particular character, the higher the tension between that character becomes. This ensures Hazumu stays good friends with the possible love interests. In order to view the ending of a particular character, a certain amount of tension will have to be between the other characters, but this cannot be too great or the ending will not show.

[Edited from Wikipedia]