The light novel "Augustus: Throne of the Supreme" is set in a medieval fantasy world featuring "Mobile Armor," advanced powered suits created using preservation magic on monster materials. The player controls Edward, the second prince of the Rinsgaya royal family, who must navigate political intrigue, sibling rivalry for the throne, and external threats. The game is known for its complex mechanics, including troop management, loyalty, and the potential for characters to die or fall into darkness early on, making a "Grand Route" ending, where all main characters survive, extremely difficult to achieve.
Chapters 3-12 introduce Todd Al Rinsgaya, the first prince and the protagonist's elder brother. Unlike the game's typical "bad end" protagonist, Todd is a reincarnated individual who retains memories of playing "Augustus." He is horrified to find himself in the body of Todd, a character destined to die in all endings. Driven by the desire to prevent the tragic fates of others and create a "True Grand End," Todd dedicates himself to rigorous training in swordsmanship under the Royal Guard Captain, Reienbach, and studies magic. He realizes that his foreknowledge of events is his greatest asset.
Todd's efforts to avert tragedy begin subtly. He trains diligently, pushing his physical and mental limits. He also begins to forge stronger bonds with his younger siblings, Edward and Enesia, and their mother, Iris. Todd actively intervenes to prevent Enesia from developing the discriminatory views inherited from her mother, particularly towards Takeru, a prince of mixed heritage. Todd's actions, such as deliberately ignoring Enesia when she insults Takeru, lead to a reconciliation between the siblings, demonstrating his growing understanding of how to shape events.
As Todd matures, his focus shifts to acquiring the technology for Mobile Armor. He recognizes the need to secure the expertise of Hartjima Iijima, a brilliant inventor from the maritime nation of Akitsushima, who is instrumental in developing advanced weaponry. Todd, now known as the "Alchemist Prince," uses his own funds to acquire materials and begins experimenting with creating his own advanced armor, "Shiranui," with the help of Reienbach, Hartjima, and Hartjima's associate, Renge. This endeavor draws the ire of his father, King Richard III, and the court, who view his pursuits as eccentric and beneath a prince. Meanwhile, Edward's intelligence and diplomatic skills begin to shine, leading many nobles to favor him as the successor.
Todd's ultimate goal is to prevent two catastrophic future events: a war with Akitsushima fueled by their development of Mobile Armor and a devastating invasion by the mountain tribes. To achieve this, he plans to recruit Hartjima and his technology to Rinsgaya and preemptively deal with the mountain tribes. He secures his father's reluctant permission for a small expedition to the Elnand mountain range, disguised as a diplomatic mission. Before departing, Todd confides in Edward about the future and the importance of Mobile Armor, entrusting him with the knowledge should anything happen to him. This conversation reveals the depth of Edward's admiration for Todd and his fear of losing his brother, highlighting their strong, non-game-like bond. The chapters conclude with Todd embarking on his mission, armed with his foreknowledge, advanced armor, and a growing team, ready to defy his predetermined fate.