The Circle Rune is a complete mystery among the 27 True Runes. It is said that this rune governs order and stagnation, and is therefore the symbol of balance. Harmonia's capital building, the Circle Palace, was likely built as some kind of tribute to this rune's longstanding power. The current bearer is the ruler of Harmonia, High Priest Hikusaak, and he has borne the rune since the Hero's War in Aronia in SY -2. However, neither Hikusaak nor his rune have been seen in hundreds of years, leading many to speculate that Hikusaak is long since dead and the rune has been missing from Harmonia for some time.

Using this rune as an absolute authority, Hikusaak, at one time, began collecting other True Runes. One of the earliest instances was the destruction of the Gate Rune Village, which Harmonia invaded and ransacked in search of the Gate Rune in the year SY 70. However, two clan sisters, Windy and Leknaat, split the rune in half and fled. This spurred a hatred within Windy, whose personal vendetta against Harmonia led her to similarly seek out other True Runes at any cost so that she could use them in her revenge. However, her plans were thwarted by Tir and the Toran Liberation Army, and she is believed to have died before she could ever take revenge on Harmonia.

For years, the True Wind Rune and the True Earth Rune had been in custody of Harmonia, and Hikusaak created two clones of himself, Luc and Sasarai, to bear them, since one can only bear one True Rune at a time. Some time before the first Fire Bringer War, under the authority of the Circle Rune, the True Lightning Rune was also held by Harmonia, but it vanished under its own free will, despite having been brought there. How this rune eventually found Geddoe, a Harmonian mercenary, has never been disclosed. The True Fire Rune was also in Harmonia's possession at the time, but a group of unified Grassland tribes infiltrated Crystal Valley, rescued their leader, and stole the True Fire Rune. It would then become the symbol of their unity as the Fire Bringer, led by the Flame Champion, who chose to bear the rune in his body. Further conflict escalated between the Grasslands and Harmonia and it did not subside until the True Fire Rune went out of control, causing a massive explosion that left both armies severely crippled.

The Flame Champion sealed the True Rune away and a truce was signed between the Grasslands and Harmonia. Years later, Harmonia showed interest in the Sun Rune. However, the involvement of a Howling Voice Guild member and the events of the Falenan Civil War put them in check and they set their eyes elsewhere. In 475, under apparent orders from Hikusaak, Harmonia sought to retrieve the True Runes it had lost fifty years prior. A bigger threat put a halt to these advances, when Luc and the Destroyers began to steal the runes from their bearers, which they planned to use to destroy the world. The Fire Bringer and Harmonia were then forced to cooperate in order to bring an end to Luc's sinister plans, which they succeeded in doing. In spite of this, Harmonia would return home without a single True Rune in their possession. Whether Hikusaak still seeks to gain control of them is still unknown.