How to Create a Revolutionary Army in Another World

The protagonist, who was involved in a traffic accident, finds himself reincarnated as the son of a nobleman in a medieval Western-style world. Regretting having done nothing in his previous life, he resolves to aim for the world's greatest swordsman in this new life. However, upon learning about the oppressed demi-human slaves and the common people suffering under corrupt rule, he decides to launch a revolution instead. He conducts business in secret from his parents, and uses the money he earns to establish a private army. By the time he reaches adulthood, he gathers all kinds of information, undergoes training, and constantly works behind the scenes for the revolution. --- Like the academy arc, there are normal fantasy elements included. The early chapters move at a brisk pace, but things settle down from Chapter 3 onwards. Also, there are no large-scale military battles for a while. It's a fantasy with a fictional war chronicle feel, utilizing modern knowledge in politics, business, strategy, espionage, and the like.