The game takes place at Habataki High School seven years after Tokimeki Girl's Side 1. There are a total of six new bachelors plus three secret characters.
TMGS 3 implements a totally new system; the Love Triangle. Instead of rival girls liking your man, all six bachelors are paired with another, making it so that you can 'date' two of them at a time. TMGS 3 also introduces a revamped clothing system with a few new clothing styles and the ability to 'level up' your fashion.

[From Tokimeki Memorial Girl's Side Wiki]