The Happy-Go-Lucky Prince of Yongle

Waking up one day, office worker Zhu Yan finds himself as the youngest brother of the Yongle Emperor—the most privileged slacker in all of Ming Dynasty. With luxurious clothes and food, and the emperor's favor, he decides: just be happy. But the Yongle era is anything but peaceful. Officials impeach him for being a parasite, princes are being stripped of titles or executed, his eldest brother Zhu Di is a ruthless killer, and the capital relocation and northern expeditions drain the people. Everyone expects this useless prince to die. Until he discovers that his jade fish pendant—when he's genuinely happy, he grows stronger. When he's happy, those around him are happy; when he's happy, even the emperor's migraines are cured. While others fight for the realm with swords and power, he uses a hotpot, a joke, and sincerity to turn the entire Yongle era into his own kingdom of joy. — Description from novelcodex.org