Nishikado (西門,Nishikado) was the tea master of the Nishikado Tea Ceremony School. He was the father of three sons, including Shoichiro and Sojiro. He regularly cheated on his wife, who knew but tolerated it. Sojiro later succeeded his father as head of the school.
Sojiro mentions his father in episode nineteen of the anime. After naming the places where he owns villas, Sojiro says "My father likes to act big although he's the head of a tea ceremony school."
Xi Men's (Sojiro) father is mentioned in episode two of Meteor Rain (2001). His wife asks Xi Men to represent him at a meeting since he is in Hong Kong. Xi Men surmises from his mother's expression that his father is seeing his mistress.
He is briefly mentioned in Hana Yori Dango Returns (2007). Like in the manga, he is the head of a tea ceremony school. His elder son left the family because he could not handle the pressure.
In Meteor Garden (2018), it is hinted that Xi Men's father is cheating on his wife. He promises to take care of her financially whether they divorce or not.