Datang: My identity as prince was exposed by Li Er

Li Yi, the eldest son of the Tang Dynasty, has a good reputation. He suffered from brain disease at the age of three and was unable to inherit the crown prince. Li Er was sent to the outskirts of Wannian County for foster care. In twelve years, His Majesty Li Er has met once in the future. Until one day, Li Yi made something called Quyuanli. Until one day, Li Yi came up with something called a facial mask. Until one day, Li Yi came up with something called black gunpowder...