Now and Then, Here and There (1999)

A Japanese boy named Shu tries to save a strange girl, Lala Ru, from kidnappers and is transported to an alternate Earth on the brink of being swallowed by the sun. There he meets an American girl from his time, Sara, who was mistakenly captured because of her resemblance to Lala Ru. Shu becomes an unwilling member of the crazy and cowardly King Hamdo's army, and Sara is forced to have sex with the adult soldiers so that she can become pregnant and bear mores soldiers or slaves. Lala Ru, who can create water--a rarity in that time--using her pendant, is both a savior and a victim in a world where factions are willing to fight and die for her abilities, and at the same time keep her locked up.