Our Father, Gou Kentarou's Secret (Chichi Gou Kentarou no Himitsu- 父・剛健太郎の秘密) - S1.E28

The injured General Dange told stories about Dr. GOU Kentarou's past when he lived in Planet Boazan. Gou was known as La Gour in Boazan and he was the son of Emperor's brother. Unfortunately, La Gour was born hornless so his parents put fake horns on his head so he could live as an aristocrat. La Gour then married a girl named Rosalia. When the Emperor died, he has no son to replace him so La Gour was chosen to be Emperor. But his cousin, Zanbajir, wanted to be Emperor and exposed La Gour's being hornless to the public. La Gour was then thrown into prison and had to worked as slave. He then managed to escape to Earth, and married Dr. Mitsuyo. From her, he got 3 sons. Kenichi and his brother were shocked to learn that they were half Boazanians. General Dange died after he had said all of this.