At Laz Meridian

At Laz Meridian (ラズ・メリディアン) is a manga series by Satoru Yuiga.

Plot
A young knight is trapped in the land of Avalon. He calls upon a ring that is supposed to grant him a new power and hope…

Mana is terrified. Her old friend Chihiro, who relentlessly teased Mana when they were younger, is moving back to Japan after a 10 year absence. As if Chihiro's brash mannerisms and bleached hair wasn't shocking enough, he gives Mana a ring with no explanation. When Mana accidentally splashes water on the ring, she finds herself transported to Avalon, where she meets the knight, Lancelot.

Avalon is a dream-like world full of magic, fairies, and people who oddly look like Mana's acquaintances from her own world. Lancelot ran away from Camelot, trying to escape from his friend King Arthur and Arthur’s betrothed, Guinevere, whom Lancelot loved. Lancelot eventually found himself lost and trapped in Avalon. As time passed, his memories of the two began to fade. However, Lancelot loved and respected both King Arthur and Guinevere, and found himself unwilling to forget. He asks Mana, the "hope" that the ring bestowed upon him, to help him escape Avalon. Does Mana, an ordinary girl who resembles Guinevere, really have the power to help Lancelot? What is the connection between her world and Avalon?