Goku trains under Kami for the next three years , once again reuniting with his friends at the '' Tenkaichi Budōkai '' , where he wins against Piccolo ; whose life he spares as it would also kill Kami .
Goku trains under Kami for the next three years , once again reuniting with his friends at the '' Tenkaichi Budōkai '' . 
 There , he defeats Piccolo , whose life he spares as it would also kill Kami .