Koriyama Castle, located in Aki-Takata City, Hiroshima Prefecture, is a mountain castle known as the residence of the Mori clan, a powerful feudal lord who ruled the Chugoku region during the Sengoku period. Mori Motonari used this castle as his base and expanded his power by winning numerous battles. Although the main part of the castle no longer remains, the vast grounds and complex layout of the enclosures (kuruwa) suggest its impregnability and the immense power of the Mori clan at the time.

It was once a huge castle that was said to be one of the largest in the Chugoku region, but now there are no buildings and many of the stone walls are crumbling.

However, it is said to have high historical value and has been selected as one of the 100 most famous castles in Japan.

Mori Motonari's grave is also there.

The castle ruins spread across Koriyama at an altitude of 390 meters, and from the remains of the main citadel near the summit, you can see the Aki-Takata city area and the surrounding mountains. The mountain paths are well maintained, making it a great place to enjoy hiking while learning about history. Remains of stone walls and moats are scattered around the area, and at each location you can reflect on the history of the Mori clan.