Simplify the following text for a Grade 8 native English-speaking person.
Original: According to Nihon Shoki , Nintoku was the fourth son of Emperor Å jin and the father of three emperors â '' RichÅ `` , Hanzei , and IngyÅ .
Simplified: According to Nihon Shoki , he was the fourth son of Emperor Å jin and the father of Emperors RichÅ `` , Hanzei , and IngyÅ .