Crystal Valley is the capital of Harmonia. It is where the "One Temple" is located and where the bulk of Harmonian politics take place. The city is said to be extremely huge--one person described that it would take a horse-drawn wagon two days to get from one side of Crystal Valley to the other side. Crystal Valley is also the location of many academies, including the Soledt Academy of Military Science and schools on rune mastery and phonology.

The city is well protected by the elite Temple Guards, but it was once penetrated by the "Flame Champion," who raided Harmonia. It is said that he sneaked into the "One Temple" and stole the True Fire Rune, but whether that is fact or fiction is in the realm of speculation.