Z is the sixth episode of the second season of Believe In Sun-Hi.
In the year 2042 on Zyth-9, Na-young is a school teacher and a hopeless romantic. She meets Ki-moon, a self-centered joker, who befriends her after she lost her job. They been going on dates and got married and had a daughter named SUN-HI.
Ki-moon and Na-young built a new home for their child, Ki-moon became a Star Collectors and Na-young becomes a nurse. That night, Na-young became heartbroken when she realized that Ki-moon had an affair with another female, Eun-ji. Na-young grabs a dagger and chased after Ki-moon (who left Eun-ji pregnant), Na-young furiously unleashes her inner asteroid and blasts Ki-moon away from Zyth-9. The next morning, the Star Collectors asks Na-young about Ki-moon, but Na-young told them that he is a trickster.
Ashamed and broken, Na-young conceived a plan to give baby Sun-Hi a better life on EARTH, by blasting her into Earth (into the ocean), keeping Sun-Hi from living "the horrible degrading secret of her father", so people would think she was an human rather than a grass nymph. The note read "Your mother love you very much", but was never properly translated. She swore to rather die than let her daughter know the "shameful truth of her origin."