Is this Homeland Dropout: The Time I Was Reincarnated as the Fourth Enchanter in the Entire World...?
He only just got reincarnated in another world as Zinc, a dropout noble, but he’s immediately banished from the kingdom?! However, that’s not enough to make Zinc just give up! With “Enchantment,” a power that can make anyone stronger by granting abilities to items, Zinc wants to make a life for himself as an adventurer. The curtain draws on Zinc’s journey as he uses this incredibly rare ability, that’s basically a cheat code, to go from zero to hero!
A man is hit by a truck and wakes up in another world as Jink, the 14-year-old heir of Duke Gordon Nonland and elder brother of the Duke's other son, Esther.
Jink was one of the guards of Crown Prince Elliot in the Kingdom of Rosalta, but is informed by his maid, Elza, that he's been dismissed by the Prince, due to his lack of talent as a spearman and his delinquent behaviour. As a result, his father has disowned him and given him a month to leave the country. He views this as a death sentence, since the world outside of the capital is full of monsters, but discovers that he's gifted with various high-level attributes, including Enchantment and Alchemy. There are only three other enchanters in this world, making him the fourth. Upon realising this, he becomes confident that he can survive in this world despite being exiled.
After leaving home, he signs up as an adventurer and in chapter 3, he meets an A-rank party called Sacred Flame, who're impressed by his abilities and invite him to travel with them to their neighbouring Kingdom of Quall. Once Jink is settled in Quall, Sacred Flame heads back to Rosalta.
In chapter 9, a meeting is held in the Royal Palace of Rosalta, with the King, the Crown Prince and various nobles in attendance. Questions are raised over why an enchanter like Jink was exiled from the Kingdom, and the Crown Prince reveals that Jink is the King's illegitimate son. The King impregnated the Chancellor's daughter and she was forced to marry Duke Nonland to make it appear that he was Jink's father.
Word of this spreads throughout the Kingdom and Esther believes that he and his family will be convicted and sentenced to slavery as a result. Preempting that, he and Elza leave the country with Sacred Flame, hoping to reunite with Jink. Unlike Esther, Elza knew the truth about Jink's birthright all along and wishes to atone for having been complicit in the cover-up. While travelling with Sacred Flame, Esther is made to cross-dress as a maid to conceal his identity.
In chapter 14, Esther and Elza catch up with Jink and offer to become his slaves, but he insists they have nothing to atone for and embraces Esther as his brother, despite knowing they're not related by blood. Esther subsequently becomes an adventurer himself and a member of Jink's party. The Kingdom of Rosalta is also shown to be in disarray, with Duke Nonland having been imprisoned, his father -- General Nobul Nonland -- beheaded by guillotine, and the King beating the Crown Prince to death with his sceptre. The Crown Prince's soul ends up in the body of an Orc General that Jink encounters in a dungeon in the following chapter. Jink kills him easily, but says he'll respawn infinitely and be killed over and over again by adventurers farming for XP and items.
In chapter 29, Duke Nonland is killed in combat as a slave soldier, and in the following chapter, Esther encounters him and Nobul as walking corpses who've been reanimated by necromancy.
