Hana no Niwa Ame no Mai

From Antisense Scanslations: Sougo Amagai has no friends at school and spends day after day alone. The only thing that gives him comfort is the feather memento a girl gave him years ago during a traditional dragon dance. Her bright smile is also engraved in his memories. Even though so long has passed, that same feather will bring them together again in the world of dragon dancing.