After Traveling Between Two Worlds, I Help the Ancients Build Infrastructure

Han Xingji is a sixteen-year-old high school senior preparing for the Gaokao, the Chinese college entrance examination. During his winter break, he maintains a late-night study livestream to combat loneliness in his empty villa. On the night of December 31st, while stepping outside to feed a stray cat, he is engulfed by a sudden blizzard and vanishes from his modern world. He awakens in a frozen wasteland, far from his home, with no signal on his phone and only a bag of cat food for sustenance. Shivering and disoriented, he spots a distant fire and trudges toward it, only to find a group of men in ragged ancient tunics who mistake him for a harbinger of death and flee in terror.

Soon after, a military patrol discovers Han Xingji in the abandoned hut. The soldiers, belonging to the Niangzi Army, are initially hostile but quickly recognize his strange, high-quality down jacket as the attire of a noble. Han Xingji, realizing he has traveled back in time to a chaotic era known as the Houyuan period, carefully constructs a cover story. He claims to be a refugee from a war-torn hometown and feigns knowledge of fortune-telling and basic medicine to avoid suspicion. When the squad leader, Yang Jingzhong, asks him to treat a sick commander, Han Xingji improvises, using his modern knowledge to diagnose pneumonia and suggesting garlic-based remedies. His survival instincts kick in as he navigates the rigid social hierarchies and life-threatening dangers of ancient warfare.

After joining the main army, Han Xingji is summoned before the Junzhu, Princess Zhaohua. Upon meeting her, he discovers she is also a transmigrator from the future. She reveals that she can return to her own time every seven days and suspects Han Xingji shares this ability since he arrived at the same moment she did. Recognizing his potential value as a link to the modern world, she proposes that he pose as her biological son. This arrangement would grant him protection and status in a society where an undocumented youth would otherwise be vulnerable. Han Xingji accepts, adopting the name A-Ji and addressing her as Mother.

His first major test comes when he is forced to treat Zhangshi Xue, the Junzhu’s husband, who is suffering from severe pneumonia. With no access to modern antibiotics, Han Xingji constructs a crude distillation apparatus to extract allicin from garlic. The treatment succeeds, stabilizing the patient and earning Han Xingji the respect of the army’s physicians. However, he remains cautious, knowing that his lack of real medical training could expose him if he pushes his luck too far. He continues to study and prepare for his eventual return, viewing his time travel as an opportunity to gain extra study time for his exams.

As the army prepares to march back to the capital, Han Xingji learns more about the political landscape. The current emperor, Han Xiao, is a figure known in his own time as the Marquis of Nanmu, a short-reigned ruler whose tomb was later discovered. The true power lies with Regent Lou Shiwei, a historical figure Han Xingji recognizes as a complex and capable leader who saved the dynasty from collapse. Han Xingji finds himself in a precarious position, caught between the loyalty of his new family and the looming political tides of a regime that is destined to fall. He must navigate court intrigues and military campaigns while waiting for the seven-day cycle to complete, hoping to find a way back to his original life without becoming a casualty of this turbulent era.