Clannad: After Story

Synopsis

One year before the events of the beginning of the story, Tomoya is beginning his second year in high school, while Nagisa is starting her third year. Nagisa is having trouble making friends as usual, while Tomoya and Youhei are busy being delinquents and carrying out pranks at Kyou's, and inadvertently Nagisa's, expense. After Nagisa is knocked out by a falling metal pan that Tomoya and Youhei had set up as a prank for freshmen, a classmate of Nagisa's finally finds the chance to talk with her and they become friends. Nagisa keeps the banner from the prank, one with the message to instill confidence written by Tomoya, because she feels it attributed her to making a new friend. (Source: Wikipedia)