Incest /Family

Brothers
There are 5 couple in this story and 4th or 5th couple come under this list.

Heavenly Emperor Huang Di, in a fit of boredom, decides to play an "egg-laying game" by sending ten of his most prized "dragons" to be reincarnated into the mortal world to produce offspring. Those who fail to do so will remain trapped there forever, never to return to the heavenly realm.