Regna

is a Japanese light novel series written by Toru Enzaki, with illustrations by Tsukasa Kotobuki. The series began publication on March 10, 1995 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
The Holy Roman Empire, which boasts a history of thousands of years, undergoes a change that shakes its foundation. Two successors to the empire who inherited the soul of the former emperor were also found. The empire cannot measure the true meaning of God and embraces his brother, sister, and two emperors. Fifteen years later, Tergio, who volunteered to be a soldier, was appointed to the Guard "Emperor's Shield" to protect his younger sister, the Emperor, for no apparent reason. Her younger sister, Emperor Fioana, in his eyes, was an unrivaled warrior, but too young, due to God-given sword skills and her dexterity. Tergio then notices the plot of her brother, Emperor SIOS, surrounding her. However, Fioana is unaware of her imminent crisis. Tergio will go to the battle with the earth god as the "emperor's shield" to protect the emperor.