Asako Igi was a magistrate under the command of the Daimyo Asako Goji. He was a battlefield veteran and well known for his talent in construction and recruitment. In 828 Goji appointed him for castle construction of what would be known as Shiro Asako. Igi commanded more than 450 of staff people, led by two Kaiu Engineers, Kaiu Motsi and Kaiu Tamiko. The castle was finished in 837.