The Solar calendar (太陽暦, Taiyoureki) is the calendar used by the Holy Kingdom of Harmonia and the earliest established calendar in the Suikoden series. It is not exclusive to Harmonia and is used in many other regions, making it something of a de facto calendar around the world.
The solar calendar begins in the year 0, the year that Hikusaak told up the mantle of High Priest within the Holy Kingdom of Harmonia. It is frequently used not only in Harmonia but in Toran and Dunan while calendar systems from other nations are frequently converted into solar calendar years. It is also widely used by historians.