"The Shield of Saiou" is a Sengoku-era historical novel built around a confrontation between castle-stone craftsmen and gunnery craftsmen.

The strongest shield and the ultimate spear collide inside a castle.

"Kokurojo" is a historical mystery built around a siege at Arioka Castle, where Araki Murashige and Kuroda Kanbei engage in a battle of deduction.

Inside a castle as a locked room, two strategists confront the case.