ビタミンX

The game is set at Seitei Gakuen, an elite private academy that teaches every level from kindergarten until college in Tokyo. Minami Yuuri is starting her second year of teaching here, and she is now moving up from teaching middle school students to the assignment she had sought after: grammar for high school students. Unfortunately, she gets assigned to "Class X," an infamous group of seniors; it is said that all of their previous teachers have retired due to ulcers or neurosis. Minami must try to reach out to these students and get them into college.

[From ANN]