Return of Ultraman (1971)

In a fight between two giant monsters named Takkong and Zazahn, young race car driver Hideki Go is killed while trying to rescue a little boy and a dog from the falling rubble. His valiant sacrifice is noted by everyone, even his friends and the new defense force MAT, but an unseen being also takes notice. Looking over Go is the "New Ultraman", who is so touched by Go's actions that he decides to combine his life force with that of Hideki, thus bringing him back to life. Hideki Go then joins the MAT and fights alongside them and Ultraman against monsters and alien invaders.