CLAMP (Mangaka group) Knihy

Umi, Hikaru, and Fuu are three schoolgirls out on a field trip to Tokyo Tower, whisked suddenly away by a strange voice and light to Cefiro, a world full of spirits and sorcery. They were summoned here through the last remaining strength of the Princess Emeraude, who hopes that they are the trio destined to become the magic knights legend says can save her realm!

Kamui is finally faced with his daunting destiny--choosing the fate of the world--and finds that his decision brings with it a terrible sacrifice.