Это как бы начало описание данного аниме данного аниме. в опенинге написано "The 1000th summer ----" черточки типо продолжение описания.
А выглядит полностью так:
The 1000th Summer is where everything begins to change and modify, this AMV is made to tell the tale of a young girl called Misuzu who stumbles across her first friends, Yukito. Going through the journey of finding the "girl in the sky" and discovering many historic past events that were forgotten memories. Song: