Ultraman (1966): Season 29, Episode 12

29 - 12: My Name

After coming to know the secret behind his birth and being defeated by Kei Fukuide, who had transformed into Pedanium Zetton, Riku lost will to live. He then received a letter from a person called Sui Asakura. Intrigued, Riku set off to visit to meet him and comes to know that he was the one who had named him "Riku".