甲山寺は薬師如来を本尊とする寺院として知られています。

甲山寺は香川県善通寺市にあり、四国巡礼で重要な地域に位置しています。

Young Kobo Daishi played in this area as a child, building mud Buddha statues and plant temples. The field where he played was called Sen-yugahara (Field Where Hermits Play).

A saint appeared from a cave on Mt. Koyama and told Kobo Daishi to build a temple there. That cave, located to the left of the Daishido Hall, became the birthplace of Koyamaji Temple.