Jaiko Gouda is the younger sister of Gian. Her first appearance was in the first chapter of the manga.
She is a short and fat girl with short black hair (brown in the 1979 anime). She usually wears a red overall skirt and white top underneath in the 1979 anime. In the 2005 anime, she has a green top with a flower on it.
At the start of the story, Jaiko is snobby and mean person who like to play prank on Nobita. This personality of her however, is short lived and in her later appearance she is shown as a kind and considerate person. Jaiko's nice personality is the total opposite of Gian's hot-blooded nature. In the 2005 remake Jaiko's personality is the same as her later appearance. Her original personality is presumbly used to create Botako, an ugly and nasty girl that rarely make appearance.
As as aspiring mangaka, Jaiko goes by her amateur Mangaka mangakastyle pen name Christine Goda (クリスチーネ 剛田 Kurisuchīne Gōda), and sometimes submits her manga to publishing companies for prizes. She mostly fails in these contest because her storytelling is still rough. After that when she decides to give up writing comic books, Gian's friends are asked/forced to cheer her up. She has a crush on Moteo Mote, a seventh grader in the school. She is sometimes referred to as Hana.
She loves to write comic books and draw. In the future, she will be a famous writer with lots of copies of her comic books sold.
Takeshi Goda -
Mrs.Goda - Mrs. Goda is very kind to her daughter and mostly treat Jaiko better than Gian because of her good behavior. She also didn't sent her to do jobs for the store like Gian. They would also sometimes cook a special meal together for Gian.
Mr.Goda - She didn't interact much with her father but they presumbly have good relationship.
In the American English dub, her nickname is changed to Little G to match with her brother dub name.