Clannad is set in a high-school located in some Japanese town. Okazaki Tomoya is a third-year student who doesn`t take his studies seriously. Always late for class, he`s seen as a delinquent by the rest of his classmates who are busy preparing for their entrance examinations. Needless to say, he hasn`t too many close friends either.

Tomoya seems not to mind too - until one day he meets a girl, Furukawa Nagisa, who is left alone without friends on this school, because everybody she knew already graduated. What a clumsy girl, he thinks at first. But he can`t leave her alone and so, while helping her, he meets a few other girls from his school. Although he doesn`t care much about them at first, he soon opens his heart to them as they get to know each other better.