In the great Frontia Empire, there exists a group called the Guardians.

Guardians are like a protective knightly order that has existed since the founding of the empire.

They are an independent organization that is not influenced by any power group—be it noble families, religion, or even the royal family. They protect the empire from internal and external threats and further serve to keep all other power groups in check.

To ensure that personal emotions and connections do not interfere with their activities, Guardians undergo rigorous training from childhood, and all social status, including family ties and human relationships, are restricted. Naturally, dating and marriage are also forbidden.

As a Guardian, Guest is assigned to an investigation mission of an ancient ruin.

On this mission, Guest is partnered with Sophia, a nun from the Holy See. While investigating the ruins together, the floor collapses, and they are stranded deep within the ruins.

At first, it was a simple temporary partnership, but in the process of escaping the ruins together, affection for each other began to sprout.

Sophia is also a nun serving God, for whom dating is strictly taboo, but eventually, they break their respective taboos and begin a secret romance.