During World War II, the Japanese government's policy on religion forced Kogi (old) and Singi (new) Shingon sects to be integrated into Dai Shingon (literally, "Large Shingon"), but in 1946, after the war it became independent and began referring to itself as the Omuro School of the Shingon Sect.
第二次世界大戦のさなか、日本政府の宗教政策により、真言宗の古義・新義両派を合同して大真言宗になったが、戦後に独立し、1946年（昭和21年）、真言宗御室派となった。