From Foes to Flames

Takes place after the tennis tournament.
Sunahara may be a delinquent, but he has a good heart. (Its the movie Version of Sunahara)

Tomoyo is heartbroken. She had let herself hope for love for the first time in a long while, yet is was crushed. She never had much luck with boys, especially because of her past. She pretends it doesn't bother her, that all boys fear her and want nothing to do with a girl like her. All hope seems lost, until Sunahara stumbled upon a sobbing Sakagami. He comforts her and attempts to cheer her up, revealing to her his careing side, and that he acts the way he does, only so others can have a smile during a boring day, and also, that he truely cares for her, as a friend, or maybe something more. She changes her view of him, and soon finds herself falling in love with him. Not wanting to have her hopes crushed again, she decided to hide them, and feels content spending time with Sunahara, as he also changes for the better. Will she keep her feeling hidden, even when it's too almost late.

PS: If you haven't watched Clannad, Clannad : After story or Clannad the movie, watch it first.