The SoulTaker: Tamashii-gari - episode 11 - 19 Jun, 2001

As Kyosuke and Komugi travel to Colony Eight, located on the moon to finally learn the truth, the Flicker girls (made up of Megumi, Kasumi, Asuka and Sayaka) await them to annihilate Kyosuke. After easily defeating them, he goes to the center of Colony Eight and finds a floating brain that turns out to be his maternal grandfather, Daigo Tokisaka, the man who caused the Beta Applicon Project seventeen years ago. He explains how he attempted to use the Beta Applicon given to him by a male alien to eradicate all disease and illness from all humankind. By injecting his own daughter, Tsubaki, who had been fatally ill the mysterious substance had miraculously saved her , which resulted in her giving birth to Richard Vincent's children; fraternal twins Kyosuke and Runa. (Source: Wikipedia)