Tsubasa: Reservoir Chronicle Volume Four is a manga by CLAMP, and it was published in North America by Del Rey Manga in 2005. The series is rated “T” for teens 13 and up; from what I’ve read of the series so far, I would agree with this rating.
Syaoran is a young man who is in love with Princess Sakura, and he is on a quest to journey through different worlds in order to find Sakura’s memories after she loses them through an unexplained event. After meeting with Yukito, the space-time witch, he gains companions to join him on his quest; however, he also had to make a deal with Yukito that involves Sakura never regaining her memories of her time with Syaoran. Syaoran’s traveling companions are Fai, Kurogane, and Mokona.
Volume Four begins the resolution of the story arc that appeared at the end of Volume Three. Sakura regains a memory; however, in a section where Syaoran is supposed to appear, all she can see is an empty chair. When Sakura tells Syaoran what she saw in her memory, it causes him to reminisce about events that were related to what Sakura saw in her memory. After Syaoran and the others arrive in the next world, it turns out to not be beneficial to the group on the journey. It’s in this portion of the story where Syaoran has his flashbacks.
The third world to appear in this volume is the setting for a little over half of the volume; unfortunately, this story arc is not resolved by the end of Volume Four. They arrive in a town where children have been vanishing mysteriously, and the townspeople believe their disappearances are tied in with a local legend. The townspeople have also developed a mistrust of outsiders. Fortunately, the town doctor defends the group and invites them to stay with him.