In an alternate present-day Japan, the Edo shogunate never fell and the Tokugawa clan continues to hold power. Fifteen years prior to the story’s beginning, a devastating attack on Edo Castle led to a complete overhaul of the capital’s defenses. As part of these new security measures, specially designated gate officials were assigned to every entrance of the castle.

The story centers on Iroha, the young and capable gate chief of the Ichibashi Gate. She is in command of a squad of handsome men who serve as a special security force, tasked with protecting and escorting members of the ruling Tokugawa family. The narrative is set in motion when Iroha receives a request to provide a guard for Tokubu, a prominent member of the Shimizu Tokugawa family.

Iroha assigns this seemingly routine escort duty to two of her subordinates, Nari and Masayama. However, the mission goes terribly wrong, and the pair return to the gate covered in severe injuries. Iroha quickly learns that their wounds resulted from the unreasonable and demanding behavior of Tokubu, the person they were meant to protect. In response, she requests that another team be assigned to the task the following day.

Instead of granting her request, Tokubu becomes intrigued by the gate chief who dared to object. Taking a liking to Iroha, he overrides her decision and issues a direct order for her to accompany him to a certain location, forcing her into a dangerous and high-stakes situation she did not want. The series follows Iroha as she navigates the complex politics and perils of serving the shogunate, dealing with the entitled and powerful members of the Tokugawa house, and leading her unit through missions that range from protective detail to facing unknown threats within the castle walls. As an ongoing series that began serialization in 2025, the full scope of the conspiracy behind the initial attack on Edo Castle and the true extent of Iroha's duties remain to be seen.