Saint☆Diary ~Kiyoka-chan no Nikki~

Saint Diary is a visual novel focusing on the romantic life of a high school student named Kiyoka (the Chinese character used to spell here name means "saint"), who works as a waitress at the local cafe during a vacation. The protagonist of the game is a male college student who frequents the cafe and gradually develops a relationship with Kiyoka. Though there are two other female characters in the game, the dating aspect focuses exclusively on Kiyoka.

[From Mobygames]