This was a four disc region 1 dvd set I got for Christmas and have been watching recently.
The story is narrated through Yuichi who hasn't seen his cousin Nayuki in years. Upon his return seemingly all his knowledge of ever visiting has vanished. He senses something vaguely familiar around his surroundings trying his best to adjust but his memory gaps haunt him as time grows ever short.
He sees in time the pieces of this puzzle, the mysterious girl with the winged backpack, a sword wielding dragon slayer and an eerie silent beauty with blazing tresses but it's up to Yuichi to discover how all these pieces of the puzzle fit together.