Dragon King Through Worlds: Brother Is My Son

As the head of the Han family in Yun City, Han Jiang travels between worlds to complete a mission. His age shifts from 60 to 20, and his original script had him dying of cancer after a lifetime of working for his family, which was rich enough to rival a nation, yet he only doted on his only son, Han Zijie, who eventually drove him to death with his sycophantic behavior. After traveling, Han Jiang receives a main mission to cultivate a family heir; every progress on the mission makes him younger. Thus, he decides to remove Han Zijie from the family tree and have another child. Coincidentally, his good friend Han Yibo also travels into this script. Initially unaware of each other and acting as enemies, they eventually unite to defeat the Dragon King, successfully complete the heir mission, and return to their original world with wealth.