This is the third volume in the saga of our beloved "sponging protagonist," and at this point, "sponging" is the last thing he's doing. A year has passed since his marriage to Queen Aura of Capua, and the capital has welcomed their new child and heir to the throne, Carlos Zenkichi. The kingdom is busy with festivities to celebrate the happy news, but something more ominous has reached Aura's ears.

Margrave Gaziel tells her that his territory has had no salt for a year, and with his lands lacking both sea and rock salt, it could spell the region's end. While the queen immediately orders an investigation, Zenjirou's free time is becoming more than he can handle in the inner palace, and he starts to investigate what advancements might be made to move their nation forward.