Oriha Kurusu is a boy belonging to the Labyrinth Information Investigation Office. The new order given to him by his boss was to protect Nagi Kunashiro, the daughter of the country's top financial conglomerate, the "Kunashiro Family," and to assist her in her daily life. Upon accepting the mission, what was handed over to him was the information on his protection target and... a single maid outfit—!? A cold-hearted young lady × the strongest bodyguard. The curtain rises on a master-servant story full of secrets—!!