Simplify the following text for a Grade 8 native English-speaking person.
Original: Jien records that Kaika was the second son of Emperor KÅ gen , and that he ruled from the palace of Isakawa-no-miya at Kasuga in what will come to be known as Yamato province .
Simplified: The GukanshÅ records that Kaika ruled from the palace of Isakawa-no-miya at Kasuga in what will come to be known as Yamato province .