Simplify the following text for a Grade 8 native English-speaking person.
Original: Nakamura Hikaru , born December 9 , 1987 in Hirakata , Japan ) is an American chess Grandmaster ( GM ) .
Simplified: Nakamura Hikaru ) is the leading U.S. chess grandmaster ( GM ) . He was born on 9 December 1987 in Japan ( Hirakata , Osaka Prefecture ) .