Hidden Princess: The Sixth Prince's Secret

Transmigrator Qin Ye hides in the Great Qian Dynasty until he bonds with Prince Chu Lan after a drunken night, awakening the Ultimate Strategist System that allows trading Earth items for strategy points. Together, they keep Lan's secret as a woman while fighting for the Crown Prince position. Third Prince Chu Sheng, backed by Prime Minister Xu Guofu, constantly tries to sabotage them, but Qin Ye uses his system to outsmart him repeatedly. In the end, Chu Lan ascends the throne to become the Great Qian's first female emperor, while Qin Ye is crowned the first male consort. Their bond grows deeper with every passing day.