Deal with a Special Condition

Princess Alexandrina is peacefully preparing for her coronation when her country is invaded by Prince Ferdinand, a claimant to the throne from a neighboring kingdom. To consolidate his rule, he plans to take Alexandrina as his wife and turn her into a silent obedient doll. To avoid such a fate and save her country, she flees and makes a deal with the elf Ien, who promises to help her reclaim the throne, but only if she does not break one special condition.