Reservoir Chronicle: Tsubasa (2005)

Syaoran, a boy who wants to become an archeologist, and Sakura, a princess from the Clow Kingdom, are childhood friends with a close relationship. On a fateful night, Sakura lost all her memories as a result of a conspiracy to obtain her powers. In order to regain her memory, Syaoran seeks help from the witch, Yuuko. Yuuko tells Syaoran that he has to travel from one alternate reality to another to collect fragments of Sakura's memory. However, even if Sakura regains her memory, she will have no recollection of Syaoran. Travelling together with them is Kurogane, a warrior who was exiled from his country, and Fye, a magician who wants to escape from his King. With the help of a magical creature, Mokona, they set off on an exciting journey through time and space.