Molt Sol Augustus is the emperor of a Roman-like civilization known only as The Empire, and thus, can be considered one of the primary antagonists of the manga and anime Gate: Thus the JSDF Fought there. Augustus is the father of two children, the crown prince Zorzal and princess Pinya. Little is known about his reign prior to his commanding an invasion through a mysterious portal known simply as "The Gate" found Alnus Hill, a location of religious significance to the Empire's religion. Augustus commands a massive army to cross the gate and seize control of the territory in his name. Unfortunately for the Imperial Army, they end up in modern-day Tokyo. The Imperial army cause no more than a few hundred civilian casualties before they are driven back the far superior firepower of the Japanese Self-Defense Force.
A few month after defeating the Imperial invasion, the Japanese launch a counter-attack through the Gate. Molt Sol Augustus orders an army of 100,000 men to attack the JSDF encampment upon Alnus Hill. Like at during their invasion of Tokyo, the JSDF easily crush the medieval-level Empire with the superior firepower of their tanks and artillery. Shortly after receiving news of the defeat, Molt reveals that it was his intent to send his rivals in court to attack Alnus, and be slaughtered by the mysterious new enemy.
Augustus attempts to halt the JSDF with a scorched earth campaign, however, he quickly realizes that the JSDF supply lines make this campaign worthless. Reluctantly, Molt makes peace with the JSDF, realize there is no way he can defeat them. This puts him at odds with both his more militant son Zorzal Caesar, and Tyuule, a former prisoner and sex slave of Zorzal's, who intends to drive the Empire into total war and annihilation at the hands of the JSDF as revenge for Zorzal's slaughter of her people.
In the most recent chapter of the manga, the head of a flame dragon slain by the Itami and his Special Region allies is turned over to the Empire. Molt parades through the Imperial capital with the Dragon's head. During the triumphal procession, Molt drinks poisoned wine and is rendered severely ill, as part of a plot by Tyuule to place Zorzal on the throne and lead the empire to a disasterous war with Japan. After Molt is rendered ill and bedridden, Zorzal stages a coup, taking full control of the Imperial Army and government.
Trivia
The anime version of Emperor Molt resembles Tywin Lannister as depicted in the TV series Game of Thrones, albeit a "younger version" with brownish blonde hair. Molt also has a similar strategic, power-hungry personality to Tywin. The manga version of Molt is completely dissimilar to the anime version, and appears much older with a gray hair and a long gray beard.