Simplify the following text for a Grade 10 native English-speaking person.
Original: According to Gackt 's autobiography , he was a mischievous child and enjoyed taking risks ; at age seven he nearly drowned while swimming off the coast of Okinawa .
Simplified: According to his autobiography , he was a mischievous child and enjoyed taking risks ; at age seven he nearly drowned while swimming off the coast of Okinawa .