Complex sentence: Trained in martial arts by Satoru Sayama, Tatsumi Kitahara began as a trainee for Japan Pro-Wrestling in 1987, but after the promotion dissolved, he was transferred to All Japan Pro Wrestling, where he was trained under Genichiro Tenryu.
Split into simpler sentences: Trained in martial arts by Satoru Sayama, Kitahara began as a trainee for Japan Pro-Wrestling in 1987. After the promotion dissolved, he transferred to All Japan Pro Wrestling and trained under Genichiro Tenryu.